Methods of communicating data including symbol mapping/demapping and related devices

ABSTRACT

Data may be transmitted from a RAN node to a wireless terminal using a MIMO antenna array. A plurality of unmapped symbol blocks may be generated. Symbols of a first one of the plurality of unmapped symbol blocks may be mapped to first and second mapped symbol blocks so that the first mapped symbol block includes symbols of the first unmapped symbol block and so that the second mapped symbol block includes symbols of the first unmapped symbol block. The symbols of the first and second mapped symbol blocks may be precoded to provide precoded symbols of respective first and second MIMO precoding layers using a MIMO precoding vector. Each of the precoded symbols of the first and second MIMO precoding layers may be transmitted through the MIMO antenna array to the wireless terminal using a same TFRE. Related devices and terminals are also discussed.

RELATED APPLICATIONS

This application claims the benefit of priority as a divisional of U.S.application Ser. No. 13/818,005 filed Feb. 20, 2013, which is a 35U.S.C. §371 national stage application of PCT International ApplicationNo. PCT/SE2012/051449, filed on Dec. 20, 2012, which claims the benefitof priority from U.S. Provisional Application No. 61/592,040 filed Jan.30, 2012. The disclosures of all of the above referenced applicationsare hereby incorporated herein in their entireties by reference.

TECHNICAL FIELD

The present disclosure is directed to wireless communications and, moreparticularly, to multiple-input-multiple-output (MIMO) wirelesscommunications and related network nodes and wireless terminals.

BACKGROUND

In a typical cellular radio system, wireless terminals (also referred toas user equipment unit nodes, UEs, and/or mobile stations) communicatevia a radio access network (RAN) with one or more core networks. The RANcovers a geographical area which is divided into cell areas, with eachcell area being served by a radio base station (also referred to as aRAN node, a “NodeB”, and/or enhanced NodeB “eNodeB”). A cell area is ageographical area where radio coverage is provided by the base stationequipment at a base station site. The base stations communicate throughradio communication channels with UEs within range of the base stations.

Moreover, a cell area for a base station may be divided into a pluralityof sectors surrounding the base station. For example, a base station mayservice three 120 degree sectors surrounding the base station, and thebase station may provide a respective directional transceiver and sectorantenna array for each sector. Stated in other words, a base station mayinclude three directional sector antenna arrays servicing respective 120degree base station sectors surrounding the base station.

Multi-antenna techniques can significantly increase capacity, datarates, and/or reliability of a wireless communication system asdiscussed, for example, by Telatar in “Capacity Of Multi-AntennaGaussian Channels” (European Transactions On Telecommunications, Vol.10, pp. 585-595, November 1999). Performance may be improved if both thetransmitter and the receiver for a base station sector are equipped withmultiple antennas (e.g., an sector antenna array) to provide amultiple-input multiple-output (MIMO) communication channel(s) for thebase station sector. Such systems and/or related techniques are commonlyreferred to as MIMO. The LTE standard is currently evolving withenhanced MIMO support and MIMO antenna deployments. A spatialmultiplexing mode is provided for relatively high data rates in morefavorable channel conditions, and a transmit diversity mode is providedfor relatively high reliability (at lower data rates) in less favorablechannel conditions.

In a downlink from a base station transmitting from a sector antennaarray over a MIMO channel to a wireless terminal in the sector, forexample, spatial multiplexing (or SM) may allow the simultaneoustransmission of multiple symbol streams over the same frequency from thebase station sector antenna array for the sector. Stated in other words,multiple symbol streams may be transmitted from the base station sectorantenna array for the sector to the wireless terminal over the samedownlink time/frequency resource element (TFRE) to provide an increaseddata rate. In a downlink from the same base station sector transmittingfrom the same sector antenna array to the same wireless terminal,transmit diversity (e.g., using space-time codes) may allow thesimultaneous transmission of the same symbol stream over the samefrequency from different antennas of the base station sector antennaarray. Stated in other words, the same symbol stream may be transmittedfrom different antennas of the base station sector antenna array to thewireless terminal over the same time/frequency resource element (TFRE)to provide increased reliability of reception at the wireless terminaldue to transmit diversity gain.

Currently, 4-layer transmission schemes are proposed forHigh-Speed-Downlink-Packet-Access (HSDPA) within Third GenerationPartnership Project (3GPP) standardization. Accordingly, up to 4codewords (where a codeword is a channel encoded transport data block)may be transmitted using a same TFRE when using 4-branch MIMOtransmission. Because channel encoding for each codeword to betransmitted during a same TFRE may require wireless terminal feedback(e.g., as CQI or channel quality information), feedback to definechannel encoding for 4 codewords may be required when using 4-branchMIMO transmission. Feedback signaling when using 4-branch MIMOtransmission may thus be undesirably high, for example, becausedifferent MIMO layers may be received at a wireless terminal during asame TFRE with different qualities, signal strengths, error rates, etc.

SUMMARY

It may therefore be an object to address at least some of the abovementioned disadvantages and/or to improve performance in a wirelesscommunication system.

According to some embodiments, data may be transmitted from a radioaccess network node to a wireless terminal using amultiple-input-multiple-output (MIMO) antenna array including aplurality of MIMO antenna elements. A plurality of unmapped symbolblocks may be generated wherein each of the unmapped symbol blocksincludes a plurality of symbols. Symbols of a first one of the pluralityof unmapped symbol blocks may be mapped to first and second mappedsymbol blocks so that the first mapped symbol block includes symbols ofthe first unmapped symbol block and so that the second mapped symbolblock includes symbols of the first unmapped symbol block. The symbolsof the first mapped symbol block may be precoded to provide precodedsymbols of a first MIMO precoding layer using a MIMO precoding vector.The symbols of the second mapped symbol block may be precoded to provideprecoded symbols of a second MIMO precoding layer using the MIMOprecoding vector. Each of the precoded symbols of the first and secondMIMO precoding layers may be transmitted through the MIMO antennaelements of the MIMO antenna array to the wireless terminal using a sametime-frequency-resource-element (TFRE). Accordingly, symbols of oneunmapped symbol block (e.g., with the unmapped symbol block provided bymodulating a data codeword) may be split between two MIMO layers.

Mapping symbols may further include mapping symbols of a second one ofthe plurality of unmapped symbol blocks to the first and second mappedsymbol blocks so that the first mapped symbol block includes symbols ofthe first and second unmapped symbol blocks and so that the secondmapped symbol block includes symbols of the first and second unmappedsymbol blocks. Accordingly, symbols of each of two unmapped symbol block(e.g., with each unmapped symbol block provided by modulating arespective data codeword) may be split between first and second MIMOlayers.

Generating the plurality of unmapped symbol blocks may include providinginput data for transmission to the wireless terminal, separating theinput data into a plurality of different data blocks, encoding a firstdata block of the plurality of different data blocks using a firstchannel code characteristic to provide a first codeword, encoding asecond data block of the plurality of different data blocks using asecond channel code characteristic different than the first channel codecharacteristic to provide a second codeword, modulating data of thefirst codeword to provide symbols of the first unmapped symbol block,and modulating data of the second codeword to provide symbols of thesecond unmapped symbol block. Accordingly, two unmapped symbol blocksmay be provided by modulating respective data codewords generating usingdifferent channel code characteristics, and symbols of the two unmappedsymbol blocks may be split between first and second MIMO layers.

Generating the plurality of unmapped symbol blocks may further includeencoding a third data block of the plurality of different data blocksusing the first channel code characteristic to provide a third codeword,and encoding a fourth data block of the plurality of different datablocks using the second channel code characteristic to provide a fourthcodeword. Moreover, modulating data of the first codeword may includeinterleaving and modulating data of the first and third codewords toprovide symbols of the first unmapped symbol block, and modulating dataof the second codeword may include interleaving and modulating data ofthe second and fourth codewords to provide symbols of the secondunmapped symbol block.

Mapping symbols of the first and second unmapped symbol blocks mayinclude combining the first unmapped symbol block and the secondunmapped symbol block to provide a combined symbol block including theplurality of symbols of the first unmapped symbol block and theplurality of symbols of the second unmapped symbol block, and separatingthe combined symbol block to generate the first and second mapped symbolblocks, so that the first mapped symbol block includes symbols of thefirst and second unmapped symbol blocks, and so that the second mappedsymbol block includes symbols of the first and second unmapped symbolblocks.

In addition, symbols of third and fourth unmapped symbol blocks of theplurality of unmapped symbol blocks may be mapped to respective thirdand fourth mapped symbol blocks, so that the third mapped symbol blockincludes symbols of the third and fourth unmapped symbol blocks, and sothat the fourth mapped symbol block includes symbols of the third andfourth unmapped symbol blocks. The symbols of the third mapped symbolblock may be precoded to provide precoded symbols of a third MIMOprecoding layer using the MIMO precoding vector, and the symbols of thefourth mapped symbol block may be precoded to provide precoded symbolsof a fourth MIMO precoding layer using the MIMO precoding vector. Eachof the precoded symbols of the first, second, third, and fourth MIMOprecoding layers may then be transmitted through the MIMO antennaelements of the MIMO antenna array to the wireless terminal using thesame time-frequency-resource-element, TFRE.

Symbols of a third unmapped symbol block of the plurality of unmappedsymbol blocks may be mapped to a third mapped symbol block, so that thethird mapped symbol block includes symbols of the third unmapped symbolblock and excludes symbols of any unmapped symbol block other than thethird unmapped symbol block. The symbols of the third mapped symbolblock may be precoded to provide precoded symbols of a third MIMOprecoding layer using the MIMO precoding vector. Each of the precodedsymbols of the first, second, and third MIMO precoding layers may thenbe transmitted through the MIMO antenna elements of the MIMO antennaarray to the wireless terminal using the sametime-frequency-resource-element (TFRE).

The TFRE may be a first TFRE. A first mapping selection from thewireless terminal may be received, wherein mapping symbols of the first,second, and third unmapped symbol blocks includes mapping responsive tothe first mapping selection, and wherein precoding the symbols of thefirst, second, and third mapped symbol blocks includes precodingresponsive to the first mapping selection. A second mapping selectionmay then be received from the wireless terminal different than the firstmapping selection. Responsive to receiving the second mapping selection,symbols of fourth and fifth unmapped symbol blocks of the plurality ofunmapped symbol blocks may be mapped to respective fourth and fifthmapped symbol blocks, so that the fourth mapped symbol block includessymbols of the fourth and fifth unmapped symbol blocks, and so that thefifth mapped symbol block includes symbols of the fourth and fifthunmapped symbol blocks. Responsive to receiving the second mappingselection, symbols of a sixth unmapped symbol block of the plurality ofunmapped symbol blocks may be mapped to a sixth mapped symbol block, sothat the sixth mapped symbol block includes symbols of the sixthunmapped symbol block and excludes symbols of any unmapped symbol blockother than the sixth unmapped symbol block. Responsive to receiving thesecond mapping selection, the symbols of the fourth mapped symbol blockmay be precoded to provide precoded symbols of the third MIMO precodinglayer using the MIMO precoding vector, the symbols of the fifth mappedsymbol block may be precoded to provide precoded symbols of the firstMIMO precoding layer using the MIMO precoding vector, and the symbols ofthe sixth mapped symbol block may be precoded to provide precodedsymbols of the second MIMO precoding layer using the MIMO precodingvector. Each of the precoded symbols of the first, second, and thirdMIMO precoding layers based on the fourth, fifth, and sixth mappedsymbol blocks may then be transmitted through the MIMO antenna elementsof the MIMO antenna array to the wireless terminal using a second TFRE.

The first mapped symbol block may include symbols of the first unmappedsymbol block and may exclude symbols of any unmapped symbol block otherthan the first unmapped symbol block, and the second mapped symbol blockmay include symbols of the first unmapped symbol block and may excludesymbols of any unmapped symbol block other than the first unmappedsymbol block. Generating the plurality of unmapped symbol blocks mayinclude providing input data for transmission to the wireless terminal,separating the input data into a plurality of different data blocks,encoding a first data block of the plurality of different data blocksusing a first channel code characteristic to provide a first codeword,and modulating data of the first codeword to provide the first unmappedsymbol block. Generating the plurality of unmapped symbol blocks mayinclude encoding a second data block of the plurality of different datablocks using the first channel code characteristic to provide a secondcodeword, and modulating data of the first codeword may includeinterleaving and modulating data of the first and second codewords toprovide the first unmapped symbol block.

According to some other embodiments, a radio access network node mayinclude a multiple-input-multiple-output (MIMO) antenna array includinga plurality of MIMO antenna elements and a processor coupled to the MIMOantenna array. The processor may be configured to generate a pluralityof unmapped symbol blocks with each of the unmapped symbol blocksincluding a respective plurality of symbols, to map symbols of a firstone of the unmapped symbol blocks of the plurality of unmapped symbolblocks to first and second mapped symbol blocks so that the first mappedsymbol block includes symbols of the first unmapped symbol blocks and sothat the second mapped symbol block includes symbols of the firstunmapped symbol blocks. The processor may be further configured toprecode the symbols of the first mapped symbol block to provide precodedsymbols of a first MIMO precoding layer using a MIMO precoding vector,and to precode the symbols of the second mapped symbol block to provideprecoded symbols of a second MIMO precoding layer using the MIMOprecoding vector. The processor may be configured to then transmit eachof the precoded symbols of the first and second MIMO precoding layersthrough the MIMO antenna elements of the MIMO antenna array to thewireless terminal using a same time-frequency-resource-element (TFRE).

The processor may be further configured to map symbols of a second oneof the plurality of unmapped symbol blocks to the first and secondmapped symbol blocks, so that the first mapped symbol block includessymbols of the first and second unmapped symbol blocks, and so that thesecond mapped symbol block includes symbols of the first and secondunmapped symbol blocks.

The processor may be further configured to generate the plurality ofunmapped symbol blocks by providing input data for transmission to thewireless terminal, separating the input data into a plurality ofdifferent data blocks, encoding a first data block of the plurality ofdifferent data blocks using a first channel code characteristic toprovide a first codeword, encoding a second data block of the pluralityof different data blocks using a second channel code characteristicdifferent than the first channel code characteristic to provide a secondcode word, modulating data of the first codeword to provide symbols ofthe first unmapped symbol block, and modulating data of the secondcodeword to provide symbols of the second unmapped symbol block.

The processor may be further configured to generate the plurality ofunmapped symbol blocks by encoding a third data block of the pluralityof different data blocks using the first channel code characteristic toprovide a third codeword, and encoding a fourth data block of theplurality of different data blocks using the second channel codecharacteristic to provide a fourth codeword. In addition, the processormay be configured to modulate data of the first code word byinterleaving and modulating data of the first and third codewords toprovide symbols of the first unmapped symbol block, and to modulate dataof the second codeword by interleaving and modulating data of the secondand fourth codewords to provide symbols of the second unmapped symbolblock.

The processor may be configured to map symbols of the first and secondunmapped symbol blocks by combining the first unmapped symbol block andthe second unmapped symbol block to provide a combined symbol blockincluding the plurality of symbols of the first unmapped symbol blockand the plurality of symbols of the second unmapped symbol block, andseparating the combined symbol block to generate the first and secondmapped symbol blocks so that the first mapped symbol block includessymbols of the first and second unmapped symbol blocks and so that thesecond mapped symbol block includes symbols of the first and secondunmapped symbol blocks.

The processor may be further configured to map symbols of third andfourth unmapped symbol blocks of the plurality of unmapped symbol blocksto respective third and fourth mapped symbol blocks so that the thirdmapped symbol block includes symbols of the third and fourth unmappedsymbol blocks and so that the fourth mapped symbol block includessymbols of the third and fourth unmapped symbol blocks. The symbols ofthe third mapped symbol block may be precoded to provide precodedsymbols of a third MIMO precoding layer using the MIMO precoding vector,and the symbols of the fourth mapped symbol block may be precoded toprovide precoded symbols of a fourth MIMO precoding layer using the MIMOprecoding vector. Each of the precoded symbols of the first, second,third, and fourth MIMO precoding layers may be transmitted through theMIMO antenna elements of the MIMO antenna array (117) to the wirelessterminal (200) using the same time-frequency-resource-element (TFRE).

The processor may be further configured to map symbols of a thirdunmapped symbol block of the plurality of unmapped symbol blocks to athird mapped symbol block so that the third mapped symbol block includessymbols of the third unmapped symbol block and excludes symbols of anyunmapped symbol block other than the third unmapped symbol block. Thesymbols of the third mapped symbol block may be precoded to provideprecoded symbols of a third MIMO precoding layer using the MIMOprecoding vector, and each of the precoded symbols of the first, second,and third MIMO precoding layers may be transmitted through the MIMOantenna elements of the MIMO antenna array to the wireless terminalusing the same time-frequency-resource-element (TFRE).

The TFRE may include a first TFRE, and the processor may be furtherconfigured to receive a first mapping selection from the wirelessterminal. Mapping symbols of the first, second, and third unmappedsymbol blocks may include mapping responsive to the first mappingselection, and precoding the symbols of the first, second, and thirdmapped symbol blocks may include precoding responsive to the firstmapping selection. The processor may be further configured to receive asecond mapping selection from the wireless terminal different than thefirst mapping selection. Symbols of fourth and fifth unmapped symbolblocks of the plurality of unmapped symbol blocks may be mapped torespective fourth and fifth mapped symbol blocks responsive to receivingthe second mapping selection so that the fourth mapped symbol blockincludes symbols of the fourth and fifth unmapped symbol blocks and sothat the fifth mapped symbol block includes symbols of the fourth andfifth unmapped symbol blocks. Symbols of a sixth unmapped symbol blockof the plurality of unmapped symbol blocks may be mapped to a sixthmapped symbol block responsive to receiving the second mapping selectionso that the sixth mapped symbol block includes symbols of the sixthunmapped symbol block and excludes symbols of any unmapped symbol blockother than the sixth unmapped symbol block. The symbols of the fourthmapped symbol block may be precoded responsive to receiving the secondmapping selection to provide precoded symbols of the third MIMOprecoding layer using the MIMO precoding vector. The symbols of thefifth mapped symbol block may be precoded responsive to receiving thesecond mapping selection to provide precoded symbols of the first MIMOprecoding layer using the MIMO precoding vector. The symbols of thesixth mapped symbol block may be precoded responsive to receiving thesecond mapping selection to provide precoded symbols of the second MIMOprecoding layer using the MIMO precoding vector. Each of the precodedsymbols of the first, second, and third MIMO precoding layers based onthe fourth, fifth, and sixth mapped symbol blocks may be transmittedthrough the MIMO antenna array to the wireless terminal using a secondTFRE.

According to still other embodiment, data may be received at a wirelessterminal from a radio access network node using amultiple-input-multiple-output (MIMO) antenna array including aplurality of MIMO antenna elements. Radio frequency signals receivedthrough the MIMO antenna elements of the MIMO antenna array may bedecoded using a MIMO decoding vector to generate a plurality of MIMOdecoded symbol layers including a first decoded symbol block of a firstof the MIMO decoded symbol layers and a second decoded symbol block of asecond of the MIMO decoded symbol layers. Moreover, the first and seconddecoded symbol blocks may represent data received during a sametime-frequency-resource-element (TFRE). Symbols of the first and seconddecoded symbol blocks may be demapped to a first unmapped symbol block,so that the first unmapped symbol block includes symbols of the firstand second decoded symbol blocks.

Demapping may further include demapping symbols of the first and seconddecoded symbol blocks to a second unmapped symbol block, so that thesecond unmapped symbol block includes symbols of the first and secondMIMO decoded symbol blocks.

In addition, the first unmapped symbol block to generate data of a firstcodeword, demodulating the second unmapped symbol block may bedemodulated to generate data of a second codeword, the first codewordmay be channel decoded using a first channel code characteristic toprovide a first data block, the second codeword may be channel decodedusing a second channel code characteristic to provide a second datablock wherein the first and second channel code characteristics aredifferent, and the first and second data blocks may be combined toprovide an output data stream.

According to yet additional embodiments, a wireless terminal may includea multiple-input-multiple output (MIMO) antenna array including aplurality of MIMO antenna elements, a receiver coupled to the MIMOantenna array wherein the receiver is configured to receive radiosignals from respective antennas of the MIMO antenna array, and aprocessor coupled to the receiver. The processor may be configured todecode the radio signals received through the receiver using a MIMOdecoding vector to generate a plurality of MIMO decoded symbol layersincluding a first decoded symbol block of a first of the MIMO decodedsymbol layers and a second decoded symbol block of a second of the MIMOdecoded symbol layers. The first and second decoded symbol blocks mayrepresent data received during a same time-frequency-resource-element.The processor may be further configured to demap symbols of the firstand second decoded symbol blocks to a first unmapped symbol block, sothat the first unmapped symbol block includes symbols of the first andsecond decoded symbol blocks.

The processor may be further configured to demap symbols of the firstand second decoded symbol blocks to a second unmapped symbol block, sothat the second unmapped symbol block includes symbols of the first andsecond MIMO decoded symbol blocks.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate certain non-limiting embodiment(s)of present inventive concepts. In the drawings:

FIGS. 1A and 1B are block diagrams illustrating communication systemsthat are configured according to some embodiments;

FIG. 2 is a block diagram illustrating a base station and a wirelessterminal according to some embodiments of FIG. 1;

FIGS. 3 and 4 are a block diagrams illustratingelements/operations/functionalities of base station processors and/ortransceivers according to some embodiments of FIG. 2;

FIG. 5 is a block diagram illustratingelements/operations/functionalities of layer mappers according to someembodiments of FIG. 4;

FIG. 6 is a block diagram illustratingelements/operations/functionalities of wireless terminal processorsand/or transceivers according to some embodiments of FIG. 2;

FIG. 7 is a schematic block diagram illustrating a 4-branch HSDPA MIMOtransmitter elements/operations/functionalities according to someembodiments;

FIGS. 8A, 8B, 8C, and 8D are diagrams illustrating codeword to layermappings according to some embodiments;

FIG. 9 is a graph illustrating layer quality as a function of layerindex according to some embodiments; and

FIGS. 10, 11A, 11B, 11C, 11D, 12, 13, 14A, 14B, 14C, 14D, 15, 16A, 16B,16C, and 16D are flow charts illustrating operations/functionalities oftransmission/reception according to some embodiments.

DETAILED DESCRIPTION

Embodiments of inventive concepts will now be described more fullyhereinafter with reference to the accompanying drawings, in whichexamples of embodiments of inventive concepts are shown. Inventiveconcepts may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of present inventiveconcepts to those skilled in the art. It should also be noted that theseembodiments are not mutually exclusive. Components from one embodimentmay be tacitly assumed to be present/used in another embodiment.

For purposes of illustration and explanation only, these and otherembodiments of present inventive concepts are described herein in thecontext of operating in a RAN (Radio Access Network) that communicatesover radio communication channels with wireless terminals (also referredto as UEs). It will be understood, however, that present inventiveconcepts are not limited to such embodiments and may be embodiedgenerally in any type of communication network. As used herein, awireless terminal (also referred to as a UE) can include any device thatreceives data from a communication network, and may include, but is notlimited to, a mobile telephone (“cellular” telephone), laptop/portablecomputer, pocket computer, hand-held computer, and/or desktop computer.

In some embodiments of a RAN, several base stations can be connected(e.g., by landlines or radio channels) to a radio network controller(RNC). The radio network controller, also sometimes termed a basestation controller (BSC), supervises and coordinates various activitiesof the plural base stations connected thereto. The radio networkcontroller is typically connected to one or more core networks.

The Universal Mobile Telecommunications System (UMTS) is a thirdgeneration mobile communication system, which evolved from the GlobalSystem for Mobile Communications (GSM), and is intended to provideimproved mobile communication services based on Wideband Code DivisionMultiple Access (WCDMA) technology. UTRAN, short for UMTS TerrestrialRadio Access Network, is a collective term for the Node B's and RadioNetwork Controllers which make up the UMTS radio access network. Thus,UTRAN is essentially a radio access network using wideband code divisionmultiple access for UEs.

The Third Generation Partnership Project (3GPP) has undertaken tofurther evolve the UTRAN and GSM based radio access networktechnologies. In this regard, specifications for the Evolved UniversalTerrestrial Radio Access Network (E-UTRAN) are ongoing within 3GPP. TheEvolved Universal Terrestrial Radio Access Network (E-UTRAN) comprisesthe Long Term Evolution (LTE) and System Architecture Evolution (SAE).

Note that although terminology from 3GPP (3^(rd) Generation PartnershipProject) HSDPA (High-Speed Downlink Packet Access) is used in thisdisclosure to exemplify embodiments of present inventive concepts, thisshould not be seen as limiting the scope of present inventive conceptsto only these systems. Other wireless systems, including WCDMA (WidebandCode Division Multiple Access), WiMax (Worldwide Interoperability forMicrowave Access), UMB (Ultra Mobile Broadband), LTE (Long TermEvolution), GSM (Global System for Mobile Communications), etc., mayalso benefit from exploiting embodiments of present inventive conceptsdisclosed herein.

Also note that terminology such as base station (also referred to aseNodeB or Evolved Node B) and wireless terminal (also referred to as UEor User Equipment) should be considered non-limiting and does not implya certain hierarchical relation between the two. In general a basestation (e.g., an “eNodeB”) and a wireless terminal (e.g., a “UE”) maybe considered as examples of respective different communications devicesthat communicate with each other over a wireless radio channel. Whileembodiments discussed herein may focus on wireless transmissions in adownlink from an eNodeB to a UE, embodiments of present inventiveconcepts may also be applied, for example, in the uplink.

FIG. 1A is a block diagram of a communication system that is configuredto operate according to some embodiments of present inventive concepts.An example RAN 60 a is shown that may be a Long Term Evolution (LTE)RAN. Radio base stations (e.g., eNodeBs) 100 a may be connected directlyto one or more core networks 70 a. In some embodiments, functionality ofa radio network controller(s) may be performed by radio base stations100 a. Radio base stations 100 a communicate over wireless channels 300a with wireless terminals (also referred to as user equipment nodes orUEs) 200 a that are within their respective communication service cells(also referred to as coverage areas). The radio base stations 100 a cancommunicate with one another through an X2 interface and with the corenetwork(s) 70 a through S1 interfaces, as is well known to one who isskilled in the art.

FIG. 1B is a block diagram of a communication system that is configuredto operate according to some other embodiments of present inventiveconcepts. An example RAN 60 b is shown that may be a WCDMA RAN. Radiobase stations (e.g., NodeBs) 100 b may be coupled to core network(s) 70b through one or more radio network controllers (RNCs) 65 b. In someembodiments, functionality of a radio network controller(s) may beperformed by radio base stations 100 b. Radio base stations 100 bcommunicate over wireless channels 300 b with wireless terminals (alsoreferred to as user equipment nodes or UEs) 200 b that are within theirrespective communication service cells (also referred to as coverageareas). The radio base stations 100 b can communicate with one anotherand with the core network(s) 70 b, as is well known to one who isskilled in the art.

FIG. 2 is a block diagram of a base station 100 (e.g., base station 100a and/or 100 b) and a wireless terminal 200 (e.g., wireless terminal 200a and/or 200 b) of FIGS. 1A and/or 1B in communication over wirelesschannel 300 (e.g., wireless channel 300 a and/or 300 b) according tosome embodiments of present inventive concepts. As shown, base station100 may include transceiver 109 coupled between processor 101 andantenna array 117 (including multiple antennas), and memory 118 coupledto processor 101. Moreover, wireless terminal 200 may includetransceiver 209 coupled between antenna array 217 and processor 201, anduser interface 221 and memory 218 may be coupled to processor 201.Accordingly, base station processor 101 may transmit communicationsthrough transceiver 109 and antenna array 117 for reception at wirelessterminal processor 201 through antenna array 217 and transceiver 209. Inthe other direction, wireless terminal processor 201 may transmitcommunications through transceiver 209 and antenna array 217 forreception at base station processor 101 through antenna array 117 andtransceiver 109. To support up to 4-branch MIMO (allowing paralleltransmission of 4 layers/streams of data using a same TFRE), each ofantenna arrays 117 and 217 may include four (or more) antenna elements.Wireless terminal 200 of FIG. 2, for example, may be a cellularradiotelephone, a smart phone, a laptop/netbook/tablet/handheldcomputer, or any other device providing wireless communications. Userinterface 211, for example, may include a visual display such as aliquid crystal display, a touch sensitive visual display, a keypad, aspeaker, a microphone, etc. As used herein, the termtime-frequency-resource-element (TFRE) may refer to atime-frequency-code-resource-element.

For MIMO downlink transmissions from RAN 60 to wireless terminal 200, acodebook of precoding vectors (known at both RAN 60 and wirelessterminal 200) is used to precode (e.g., to apply precoding weights to)the different MIMO data layers (data streams) that are transmitted inparallel from a sector antenna array(s) to the wireless terminal 200during a same TFRE, and to decode the MIMO data layers (data streams)received in parallel during the same TFRE at wireless terminal 200. Thesame codebook of precoding vectors may be stored in wireless terminalmemory 218 and in base station memory 118. Moreover, wireless terminal200 may estimate characteristics of each downlink channel to generatechannel quality information (CQI), and CQI feedback from wirelessterminal 200 may be transmitted to base station 100. This CQI feedbackmay then be used by the base station processor 101 to select:transmission rank (i.e., a number of data layers/streams to betransmitted during a subsequent TFRE); transport data block length(s);channel code rate(s) to be used to channel encode different transportdata blocks; modulation order(s); symbol to layer mapping schemes;and/or precoding vectors for respective downlink transmissions to thewireless terminal 200.

By way of example, base station antenna array 117 may include 4antennas, and wireless terminal antenna array 217 may include fourantennas so that wireless terminal 200 may receive up to four downlinkdata layers (data streams) from base station antenna array 117 duringMIMO communications. In this example, the precoding codebook may includerank 1 precoding vectors (used when transmitting one downlink datastream from a base station sector antenna array 117 to wireless terminal200), rank 2 precoding vectors (used when transmitting two downlink datastreams from a base station sector antenna array 117 to wirelessterminal 200), rank 3 precoding vectors (used when transmitting threedownlink data streams from a base station sector antenna array 117 towireless terminal 200), and rank 4 precoding vectors (used whentransmitting four downlink data streams from a base station sectorantenna array 117 to wireless terminal 200). Precoding vectors may alsobe referred to, for example, as codebook entries, precoding codewords,and/or precoding matrices.

FIG. 3 is block diagram illustrating elements/functionalities of basestation processor 101 and/or transceiver 109 of FIG. 2 according to someembodiments. According to embodiments of FIG. 3, functionality of twochannel encoders CE1 and CE2 may be provided for two streams oftransport data blocks B1 and B2, with symbols of the two data streamsbeing mapped to as many as four different MIMO data streams. As shown,processor 101 may include transport data block generator 301, channelencoder 303, modulator 305, layer mapper 307, spreader/scrambler 309,and layer precoder 311. In embodiments of FIG. 3, channel encoder 303may include channel encoders CE1 and CE2 for the two streams oftransport data blocks B1 and B2, modulator 305 may includeinterleavers/modulators IM1 and IM2, and layer mapper 307 may beconfigured to map resulting symbols of the two streams to as many asfour different MIMO layers (streams) X1, X2, X3, and X4 as discussed ingreater detail below. Moreover, adaptive controller 315 may beconfigured to control transport data block generator 301, channelencoder 303, modulator 305, layer mapper 307, and/or layer precoder 311responsive to channel quality information (CQI) received as feedbackfrom wireless terminal 200. Accordingly, symbols generated responsive to2 codewords respectively generated by channel encoders CE1 and CE2 usingdifferent channel coding characteristics (determined by adaptivecontroller 315 responsive to wireless terminal 200 feedback) may bedistributed (mapped) to 4 different MIMO layers. More generally, symbolsgenerated responsive to a single codeword may be split between differentMIMO layers.

Base station processor 101, for example, may receive input data (e.g.,from core network 70, from another base station, etc.) for transmissionto wireless terminal 200, and transport data block generator 301(including transport data block data generators TB1 and TB2) mayseparate the input data into a plurality of different data blocks(comprising respective data bits). More particularly, for rank 1transmissions (providing only 1 MIMO layer/stream), all input data maybe processed through transport data block generator TB1 to provide asingle stream of transport data blocks B1 (including individualtransport data blocks b1-1, b1-2, b1-3, etc.) without using transportdata block generator TB2 and without generating a second stream oftransport data blocks B2. For rank 2 transmissions (providing 2 MIMOlayers/streams), rank 3 transmissions (providing 3 MIMO layers/streams),and rank 4 transmissions (providing 4 MIMO layers/streams), transportdata block generator TB1 may generate a stream of transport data blocksB1 (including individual transport data blocks b1-1, b1-2, b1-3, etc.),and transport data block generator TB2 may generate a stream oftransport data blocks B2 (including individual transport data blocksb2-1, b2-2, b2-3, etc.).

Channel encoder 303 (including channel encoders CE1 and CE2) may encodethe stream/streams of data blocks B1 and/or B2 generated by transportdata block generator 301 to provide respective streams of data codewordsCW1 (including individual data codewords cw1-1, cw1-2, cw1-3, etc.) andCW2 (including individual data codewords cw2-1, cw2-2, cw2-3, etc.), forexample, using turbo coding, convolutional coding, etc. Moreover, codingcharacteristics (e.g., coding rates) applied by channel encoders CE1 andCE2 may be separately determined by adaptive controller 315 responsiveto wireless terminal 200 feedback (e.g., CQ1 regarding the downlinkchannel). For rank 1 transmissions, channel encoder 303 may generate asingle stream of data codewords CW1 responsive to the stream of datablocks B1 using only channel encoder CE1. For rank 2, rank 3, and rank 4transmissions, channel encoder 303 may generate two streams of datacodewords CW1 and CW2 responsive to respective streams of data blocks B1and B2 using channel encoder CE1 and channel encoder CE2. According tosome embodiments, channel encoders CE1 and CE2 may apply differentcoding characteristics (e.g., different coding rates) during rank 2,rank 3, and rank 4 transmissions to generate respective (differentlycoded) data codewords cw1-1 and cw2-1 including data to be transmittedduring a same TFRE.

Modulator 305 (including interleaver/modulator IM1 andinterleaver/modulator IM2) may interleave and modulate thestream/streams of data codewords CW1 and/or CW2 generated by channelencoder 303 to provide respective streams of unmapped symbol blocks D1(including unmapped symbol blocks d1-1, d1-2, d1-3, etc.) and D2(including unmapped symbol blocks d2-1, d2-2, d2-3, etc.). For rank 1transmissions (providing only 1 MIMO layer/stream), modulator 305 maygenerate a single stream of unmapped symbol blocks D1 responsive to thestream of data codewords CW1 using only interleaver/modulator IM1. Forrank 2, rank 3, and rank 4 transmissions, modulator 305 may generate twostreams of unmapped symbol blocks D1 and D2 responsive to respectivestreams of data codewords CW1 and CW2 using interleaver/modulator IM1and interleaver/modulator IM2. Modulator 305 may apply modulation ordersresponsive to input from adaptive controller 315 determined based on CQIfeedback from wireless terminal 200.

In addition, each interleaver/modulator IM1 and/or IM2 may interleavedata of two or more codewords of a respective stream so that two or moreunmapped symbol blocks of a stream include symbols representing data ofthe two or more codewords. For example, data of consecutive datacodewords cw1-1 and cw1-2 of data codeword stream CW1 may be interleavedand modulated to provide consecutive unmapped symbol blocks d1-1 andd1-2 of stream D1. Similarly, data of consecutive data codewords cw2-1and cw2-2 of data codeword stream CW2 may be interleaved and modulatedto provide consecutive unmapped symbol blocks d2-1 and d2-2 of streamD2.

Symbols of streams of unmapped symbol blocks D1 and D2 may be mapped torespective streams of mapped symbol blocks X1, X2, X3, and X4, asdiscussed in greater detail below. For rank one transmissions, all inputdata may be processed through transport data block generator TB1 toprovide a single stream of transport data blocks B1, the single streamof transport data blocks may be encoded using channel encoder CE1 toprovide a single stream of data codewords CW1, and the single stream ofcodewords may be interleaved/modulated using interleaver and modulatorIM1 to provide a single stream of unmapped symbol blocks D1. Symbols ofthe single stream of unmapped symbol blocks D1 may be mapped to a singlestream of mapped symbol blocks X1 (including mapped symbol blocks x1-1,x1-2, x1-3, etc.). Each unmapped symbol block d and each mapped symbolblock x, for example, may include M symbols such that each unmappedsymbol block d includes symbols d(i) and each mapped symbol block xincludes symbols x(i), where i=1 to M. With rank 1 transmissions,symbols d1-1(i) of unmapped symbol block d1-1 may thus map directly tosymbols x1-1(i) of mapped symbol block x1-1, symbols d1-2(i) of unmappedsymbol block d1-2 may map directly to symbols x1-2(i) of mapped symbolblock x1-2, symbols d1-3(i) of unmapped symbol block d1-3 may mapdirectly to symbols x1-3(i) of mapped symbol block x1-3, etc.

Stated in other words, for rank 1 transmissions, x1-j(i)=d1-j(i), wherej identifies the block of the stream of unmapped symbol blocks D1 andmapped symbol blocks X1. With rank one transmissions, only one stream ofunmapped symbol blocks D1 and only one stream of mapped symbol blocks X1may be used for the single layer MIMO transmissions. Spreader &scrambler 309 may include a plurality of spreaders/scramblers SS1, SS2,SS3, and SS4, but with only one stream of mapped symbol blocks X1 forone layer MIMO transmission, only one spreader/scrambler SS1 is used tospread/scramble the stream of mapped symbol blocks (e.g., using a Walshcode) to provide a stream of spread symbols blocks Y1 (including spreadsymbol blocks y1-1, y1-2, y1-3, etc.), and layer precoder 311 may applya rank 1 MIMO precoding vector to precode (e.g., to apply precodingweights to) the stream of spread symbol blocks Y1 for transmissionthrough transceiver 109 and antennas Ant-1, Ant-2, Ant-3, and Ant-4 ofantenna array 117.

For rank two transmissions, input data may be processed throughtransport data block generators TB1 and TB2 to provide two streams oftransport data blocks B1 and B2, the two streams of transport datablocks may be encoded using channel encoders CE1 and CE2 (e.g., usingdifferent coding characteristics/rates) to provide two streams of datacodewords CW1 and CW2, and the two streams of codewords may beinterleaved/modulated using interleavers/modulators IM1 and IM2 toprovide two streams of unmapped symbol blocks D1 and D2. Symbols of thetwo streams of unmapped symbol blocks D1 and D2 may be mapped torespective streams of mapped symbol blocks X1 (including mapped symbolblocks x1-1, x1-2, x1-3, etc.) and X2 (including mapped symbol blocksx1-1, x1-2, x1-3, etc.). Each unmapped symbol block d of streams D1 andD2 and each mapped symbol block x of streams X1 and X2, for example, mayinclude M symbols such that each unmapped symbol block d includessymbols d(i) and each mapped symbol block x includes symbols x(i), wherei=1 to M. With rank 2 transmissions: symbols d1-1(i) of unmapped symbolblock d1-1 may map directly to symbols x1-1(1) of mapped symbol blockx1-1, and symbols d2-1(i) of unmapped symbol block d2-1 may map directlyto symbols x2-1(i) of mapped symbol block x2-1; symbols d1-2(i) ofunmapped symbol block d1-2 may map directly to symbols x1-2(i) of mappedsymbol block x1-2, and symbols d2-2(i) of unmapped symbol block d2-2 maymap directly to symbols x2-2(i) of mapped symbol block x2-2; symbolsd1-3(i) of unmapped symbol block d1-3 may map directly to symbolsx1-3(i) of mapped symbol block x1-3, and symbols d2-3(i) of unmappedsymbol block d2-3 may map directly to symbols x2-3(i) of mapped symbolblock x2-3; etc.

Stated in other words, for rank 2 transmissions, x1-j(i)=d1-j(i), andx2-j(i)=d2-j(i), where j identifies the block of the stream of unmappedsymbol blocks D1/D2 and mapped symbol blocks X1/X2. With rank twotransmissions, only two streams of unmapped symbol blocks D1 and D2 andonly two streams of mapped symbol blocks X1 and X2 may be used for thetwo layer MIMO transmissions. Spreader/scrambler 309 may include aplurality of spreaders/scramblers SS1, SS2, SS3, and SS4, but with onlytwo streams of mapped symbol blocks X1 and X2, only twospreader/scramblers SS1 and SS2 are used to spread/scramble the twostreams of mapped symbol blocks (e.g., using a Walsh code) to providestreams of spread symbols blocks Y1 (including spread symbol blocksy1-1, y1-2, y1-3, etc.) and Y2 (including spread symbol blocks y2-1,y2-2, y2-3, etc.), and layer precoder 311 may apply a rank 2 MIMOprecoding vector to precode (e.g., to apply precoding weights to) thestreams of spread symbol blocks Y1 and Y2 for transmission throughtransceiver 109 and antennas Ant-1, Ant-2, Ant-3, and Ant-4 of antennaarray 117.

For rank three transmissions, input data may be processed throughtransport data block generators TB1 and TB2 to provide two streams oftransport data blocks B1 and B2. Because the input data will betransmitted using three MIMO transmission layers, transport data blockgenerator 301 may bundle transport block data so that transport datablocks of one of streams B1 or B2 may include data of two conventionaldata blocks. The two streams of transport data blocks B1 and B2 may beencoded using channel encoders CE1 and CE2 (e.g., using different codingcharacteristics/rates) to provide two streams of data codewords CW1 andCW2, and the two streams of codewords may be interleaved/modulated usinginterleavers/modulators IM1 and IM2 to provide two streams of unmappedsymbol blocks D1 and D2.

Symbols of one of the streams of unmapped symbol blocks may be mapped toa single one of the streams of mapped symbol blocks, and symbols of theother of the streams of unmapped symbol blocks may be mapped to twoother streams of mapped symbol blocks. For example, symbols from thestream of unmapped symbol blocks D1 may be mapped directly to symbols ofthe stream of mapped symbol blocks X1, and symbols of the stream ofunmapped symbol blocks D2 may be split between streams of mapped symbolblocks X2 and X3; or symbols from the stream of unmapped symbol blocksD2 may be mapped directly to symbols of the stream of mapped symbolblocks X2, and symbols of the stream of unmapped symbol blocks D1 may besplit between streams of mapped symbol blocks X1 and X3; or symbols fromthe stream of unmapped symbol blocks D2 may be mapped directly tosymbols of the stream of mapped symbol blocks X3, and symbols of thestream of unmapped symbol blocks D1 may be split between streams ofmapped symbol blocks X1 and X2.

Stated in other words, for rank 3 transmissions mappings from unmappedto mapped symbol blocks may be provided according to one of thefollowing options.

FIG. 3, Rank 3, Option 1

x1-j(i)=d1-j(i);

x2-j(i)=d2-j(2 i); and

x3-j(i)=d2-j(2 i+1).

According to Option 1, symbols of unmapped blocks d1-j from stream D1map directly to symbols of mapped blocks x1-j of stream X1, even symbolsof unmapped blocks d2-j from stream D2 map to symbols of mapped blocksx2-j of stream X2, and odd symbols of unmapped blocks d2-j from streamD2 map to symbols of mapped blocks x3-j of stream X3.

FIG. 3, Rank 3, Option 2

x2-j(i)=d2-j(i);

x1-j(i)=d1-j(2 i); and

x3-j(i)=d1-j(2 i+1).

According to Option 2, symbols of unmapped blocks d2-j from stream D2map directly to symbols of mapped blocks x2-j of stream X2, even symbolsof unmapped blocks d1-j from stream D1 map to symbols of mapped blocksx1-j of stream X1, and odd symbols of unmapped blocks d1-j from streamD1 map to symbols of mapped blocks x3-j of stream X3.

FIG. 3, Rank 3, Option 3

x3-j(i)=d2-j(i);

x1-j(i)=d1-j(2 i); and

x2-j(i)=d1-j(2 i+1).

According to Option 3, symbols of unmapped blocks d2-j from stream D2map directly to symbols of mapped blocks x3-j of stream X3, even symbolsof unmapped blocks d1-j from stream D1 map to symbols of mapped blocksx1-j of stream X1, and odd symbols of unmapped blocks d1-j from streamD1 map to symbols of mapped blocks x2-j of stream X2.

With rank three transmissions, only two streams of unmapped symbolblocks D1 and D2 and are mapped to three streams of mapped symbol blocksX1, X2, and X3 for three layer MIMO transmissions. Spreader/scrambler309 may include a plurality of spreaders/scramblers SS1, SS2, SS3, andSS4, but with only three streams of mapped symbol blocks X1, X2, and X3for three MIMO transmission layers, only three spreader/scramblers SS1and SS2 are used to spread/scramble the three streams of mapped symbolblocks (e.g., using a Walsh code) to provide streams of spread symbolsblocks Y1 (including spread symbol blocks y1-1, y1-2, y1-3, etc.), Y2(including spread symbol blocks y2-1, y2-2, y2-3, etc.), and Y3(including spread symbol blocks y3-1, y3-2, y3-3, etc.). Layer precoder311 may apply a rank 3 MIMO precoding vector to precode (e.g., to applyprecoding weights to) the streams of spread symbol blocks Y1, Y2, and Y3for transmission through transceiver 109 and antennas Ant-1, Ant-2,Ant-3, and Ant-4 of antenna array 117.

For rank four transmissions, input data may be processed throughtransport data block generators TB1 and TB2 to provide two streams oftransport data blocks B1 and B2. Because the input data will betransmitted using four MIMO transmission layers, transport data blockgenerator 301 may bundle transport block data so that transport datablocks of both of streams B1 and B2 may include data of two conventionaldata blocks. The two streams of transport data blocks B1 and B2 may beencoded using channel encoders CE1 and CE2 (e.g., using different codingcharacteristics/rates) to provide two streams of data codewords CW1 andCW2, and the two streams of codewords may be interleaved/modulated usinginterleavers/modulators IM1 and IM2 to provide two streams of unmappedsymbol blocks D1 and D2.

Symbols of both streams of unmapped symbol blocks may be mapped torespective different pairs of streams of mapped symbol blocks. Forexample, symbols from the stream of unmapped symbol blocks D1 may besplit between streams of mapped symbol blocks X1 and X3, and symbols ofthe stream of unmapped symbol blocks D2 may be split between streams ofmapped symbol blocks X2 and X4; or symbols from the stream of unmappedsymbol blocks D1 may be split between streams of mapped symbol blocks X1and X4, and symbols of the stream of unmapped symbol blocks D2 may besplit between streams of mapped symbol blocks X2 and X3; or symbols fromthe stream of unmapped symbol blocks D1 may split between streams ofmapped symbol blocks X1 and X2, and symbols of the stream of unmappedsymbol blocks D2 may be split between streams of mapped symbol blocks X3and X4.

Stated in other words, for rank 4 transmissions mappings from unmappedto mapped symbol blocks may be provided according to one of thefollowing options.

FIG. 3, Rank 4, Option 1

x1-j(i)=d1-j(2 i);

x3-j(i)=d1-j(2 i+1);

x2-j(i)=d2-j(2 i); and

x4-j(i)=d2-j(2 i+1).

According to Option 1, even symbols of unmapped blocks d1-j from streamD1 map to symbols of mapped blocks x1-j of stream X1, odd symbols ofunmapped blocks d1-j from stream D1 map to symbols of mapped blocks x3-jof stream X3, even symbols of unmapped blocks d2-j from stream D2 map tosymbols of mapped blocks x2-j of stream X2, and odd symbols of unmappedblocks d2-j from stream D2 map to symbols of mapped blocks x4-j ofstream X4.

FIG. 3, Rank 4, Option 2

x1-j(i)=d1-j(2 i);

x4-j(i)=d1-j(2 i+1);

x3-j(i)=d2-j(2 i); and

x2-j(i)=d2-j(2 i+1).

According to Option 2, even symbols of unmapped blocks d1-j from streamD1 map to symbols of mapped blocks x1-j of stream X1, odd symbols ofunmapped blocks d1-j from stream D1 map to symbols of mapped blocks x4-jof stream X4, even symbols of unmapped blocks d2-j from stream D2 map tosymbols of mapped blocks x3-j of stream X3, and odd symbols of unmappedblocks d2-j from stream D2 map to symbols of mapped blocks x2-j ofstream X2.

FIG. 3, Rank 4, Option 3

x1-j(i)=d1-j(2 i);

x2-j(i)=d1-j(2 i+1);

x3-j(i)=d2-j(2 i); and

x4-j(i)=d2-j(2 i+1).

According to Option 3, even symbols of unmapped blocks d1-j from streamD1 map to symbols of mapped blocks x1-j of stream X1, odd symbols ofunmapped blocks d1-j from stream D1 map to symbols of mapped blocks x2-jof stream X2, even symbols of unmapped blocks d2-j from stream D2 map tosymbols of mapped blocks x3-j of stream X3, and odd symbols of unmappedblocks d2-j from stream D2 map to symbols of mapped blocks x4-j ofstream X4.

With rank four transmissions, only two streams of unmapped symbol blocksD1 and D2 and are mapped to four streams of mapped symbol blocks X1, X2,X3, and X4 for four layer MIMO transmissions. Spreader & scrambler 309may use spreaders/scramblers SS1, SS2, SS3, and SS4 to spread/scramblethe four streams of mapped symbol blocks (e.g., using a Walsh code) toprovide streams of spread symbols blocks Y1 (including spread symbolblocks y1-1, y1-2, y1-3, etc.), Y2 (including spread symbol blocks y2-1,y2-2, y2-3, etc.), Y3 (including spread symbol blocks y3-1, y3-2, y3-3,etc.), and Y4 (including spread symbol blocks y4-1, y4-2, y4-3, etc.).Layer precoder 311 may apply a rank 4 MIMO precoding vector to precode(e.g., to apply precoding weights to) the streams of spread symbolblocks Y1, Y2, Y3, and Y4 for transmission through transceiver 109 andantennas Ant-1, Ant-2, Ant-3, and Ant-4 of antenna array 117.

According to embodiments discussed above with respect to FIG. 3, CQIfeedback information from wireless terminal 200 may be reduced therebyreducing traffic over a feedback channel from wireless terminal 200 tobase station 100. By using only two transport block generators TB1 andTB2 so that transport blocks are bundled at the bit level for rank 3 andrank 4 transmissions, CQI feedback used to define transport block lengthmay be reduced. By using only two channel encoders CE1 and CE2 tosupport 3 and 4 layer MIMO transmissions (rank 3 and rank 4transmissions), CQI feedback used to define channel code rates may bereduced. By using only two interleavers/modulators IM1 and IM2 tosupport 3 and 4 layer MIMO transmissions, CQI feedback used to definemodulation orders may be reduced.

According to some embodiments of FIG. 3, layer mapper 307 may applyfixed mapping functions (known to both base station 100 and wirelessterminal 200) for rank 3 and rank 4 transmissions. For Rank 3transmission, for example, layer mapper 307 may always use the rank 3option 1 mapping such that x1-j(i)=d1-j(i), x2-j(i)=d2-j(2 i), andx3-j(i)=d2-j(2 i+1), and for Rank 4 transmission, layer mapper 307 mayalways use the rank 4 option 1 mapping such that x1-j(i)=d1-j(2 i),x3-j(i)=d1-j(2 i+1), x2-j(i)=d2-j(2 i), and x4-j(i)=d2-j(2 i+1). Usingfixed mappings may reduce control channel traffic that may otherwise beneeded to signal mapping selections/recommendations between base station100 and wireless terminal 200.

According to some other embodiments of FIG. 3, mapping functions forrank 3 and rank 4 transmissions may be dynamically selected. Wirelessterminal processor 201, for example, may select from a plurality ofmapping function options (e.g., one of options 1-3 for rank 3 or one ofoptions 1-3 for rank 4 as discussed above), and this selection may beidentified in CQI feedback that is transmitted to base station 100 for asubsequent downlink transmission. More particularly, a rank selectionmay be included in the CQI feedback, and an additional 2 bit code may beused to identify one of options 1-3 for rank 3 transmissions or one ofoptions 1-3 for rank 4 transmissions. Wireless terminal processor 201may thus chose a mapping option to increase a quality and/or rate ofdata transmission over the downlink. According to other embodiments,adaptive controller 315 may select the mapping option for rank 3 andrank 4 transmissions, and the selection may be signaled to wirelessterminal 200.

FIG. 4 is block diagram illustrating elements/functionalities of basestation processor 101 and/or transceiver 109 of FIG. 2 according to someother embodiments. According to embodiments of FIG. 4, functionality offour channel encoders CE1, CE2, CE3, and CE4 may be provided for fourstreams of transport data blocks B1, B2, B3, and B4, with symbols of thefour data streams being mapped to as many as four different datastreams. As shown, processor 101 and/or transceiver 109 mayinclude/provide functionality of transport data block generator 401,channel encoder 403, modulator 405, layer mapper 407, spreader/scrambler409, and layer precoder 411. In embodiments of FIG. 4, channel encoder403 may include/provide functionality of channel encoders CE1, CE2, CE3,and CE4 for the four streams of transport data blocks B1, B2, B3, andB4, modulator 405 may include/provide functionality ofinterleavers/modulators IM1, IM2, IM3, and IM4, and layer mapper 407 maybe configured to map resulting symbols of the four streams to as many asfour different MIMO layers (streams) X1, X2, X3, and X4 as discussed ingreater detail below. Moreover, adaptive controller 415 may beconfigured to control transport data block generator 401, channelencoder 403, modulator 405, layer mapper 407, and/or layer precoder 411responsive to channel quality information (CQI) received as feedbackfrom wireless terminal 200. Accordingly, symbols generated responsive tocodewords respectively generated by channel encoders CE1, CE2, CE3, andCE4 using different channel coding (determined by adaptive controller415 responsive to wireless terminal 200 feedback) may be interleaved anddistributed (mapped) to 4 different MIMO layers. More particularly,symbols generated responsive to two codewords may be interleaved andthen split between two different MIMO layers.

Base station processor 101, for example, may receive input data (e.g.,from core network 70, from another base station, etc.) for transmissionto wireless terminal 200, and transport data block generator 401(including transport data block data generators TB1, TB2, TB3, and TB4)may provide a single stream of data blocks (for rank 1 transmissions) orseparate the input data into a plurality of different streams of datablocks (for rank 2, rank 3, and rank 4 transmission). More particularly,for rank 1 transmissions (providing only 1 MIMO layer/stream), all inputdata may be processed through transport data block generator TB1 toprovide a single stream of transport data blocks B1 (includingindividual transport data blocks b1-1, b1-2, b1-3, etc.) without usingtransport data block generators TB2, TB3, or TB4 and without generatingother streams of transport data blocks B2, B3, or B4. For rank 2transmissions (providing 2 MIMO layers/streams), transport data blockgenerator TB1 may generate a stream of transport data blocks B1(including individual transport data blocks b1-1, b1-2, b1-3, etc.), andtransport data block generator TB2 may generate a stream of transportdata blocks B2 (including individual transport data blocks b2-1, b2-2,b2-3, etc.) without using transport data block generators TB3 or TB4 andwithout generating other streams of transport data blocks B3 or B4. Forrank 3 transmissions (providing 3 MIMO layers/streams), transport datablock generator TB1 may generate a stream of transport data blocks B1(including individual transport data blocks b1-1, b1-2, b1-3, etc.),transport data block generator TB2 may generate a stream of transportdata blocks B2 (including individual transport data blocks b2-1, b2-2,b2-3, etc.), and transport data block generator TB3 may generate astream of transport data blocks B3 (including individual transport datablocks b3-1, b3-2, b3-3, etc.), without using transport data blockgenerator TB4 and without generating another stream of transport datablocks B4. For rank 4 transmissions (providing 4 MIMO layers/streams),transport data block generator TB1 may generate a stream of transportdata blocks B1 (including individual transport data blocks b1-1, b1-2,b1-3, etc.), transport data block generator TB2 may generate a stream oftransport data blocks B2 (including individual transport data blocksb2-1, b2-2, b2-3, etc.), transport data block generator TB3 may generatea stream of transport data blocks B3 (including individual transportdata blocks b3-1, b3-2, b3-3, etc.), and transport data block generatorTB4 may generate a stream of transport data blocks B4 (includingindividual transport data blocks b4-1, b4-2, b4-3, etc.).

Channel encoder 403 (including channel encoders CE1, CE2, CE3, and CE4)may encode the stream/streams of data blocks B1, B2, B3, and/or B4generated by transport data block generator 401 to provide respectivestreams of data codewords CW1 (including individual data codewordscw1-1, cw1-2, cw1-3, etc.), CW2 (including individual data codewordscw2-1, cw2-2, cw2-3, etc.), CW3 (including individual data codewordscw3-1, cw3-2, cw3-3, etc.), and/or CW4 (including individual datacodewords cw4-1, cw4-2, cw4-3, etc.), for example, using turbo coding,convolutional coding, etc. Moreover, coding characteristics (e.g.,coding rates) applied by channel encoders CE1, CE2, CE3, and CE4 may beseparately determined by adaptive controller 415 responsive to wirelessterminal 200 feedback (e.g., CQI regarding the downlink channel). Forrank 1 transmissions, channel encoder 403 may generate a single streamof data codewords CW1 responsive to the stream of data blocks B1 usingonly channel encoder CE1. For rank 2 transmissions, channel encoder 403may generate two streams of data codewords CW1 and CW2 responsive torespective streams of data blocks B1 and B2 using channel encoder CE1and channel encoder CE2. For rank 3 transmissions, channel encoder 403may generate three streams of data codewords CW1, CW2, and CW3responsive to respective streams of data blocks B1, B2, and B3 usingchannel encoder CE1, channel encoder CE2, and channel encoder CE3. Forrank 4 transmissions, channel encoder 403 may generate four streams ofdata codewords CW1, CW2, CW3, and CW4 responsive to respective streamsof data blocks B1, B2, B3, and B4 using channel encoder CE1, channelencoder CE2, channel encoder CE3, and channel encoder CW4. According tosome embodiments, channel encoders CE1, CE2, CE3, and/or CE4 may applydifferent coding characteristics (e.g., different coding rates) duringrank 2, rank 3, and/or rank 4 transmissions to generate respective(differently coded) data codewords cw1-1, cw2-1, cw3-1, and/or cw4-1including data to be transmitted during a same TFRE.

Modulator 405 (including interleaver/modulators IM1, IM2, IM3, and IM4)may interleave and modulate the stream/streams of data codewords CW1,CW2, CW3, and/or CW4 generated by channel encoder 403 to providerespective streams of unmapped symbol blocks D1 (including unmappedsymbol blocks d1-1, d1-2, d1-3, etc.), D2 (including unmapped symbolblocks d2-1, d2-2, d2-3, etc.), D3 (including unmapped symbol blocksd3-1, d3-2, d3-3, etc.), and/or D4 (including unmapped symbol blocksd4-1, d4-2, d4-3, etc.). For rank 1 transmissions (providing only 1 MIMOlayer/stream), modulator 405 may generate a single stream of unmappedsymbol blocks D1 responsive to the stream of data codewords CW1 usingonly interleaver/modulator IM1. For rank 2 transmissions, modulator 405may generate two streams of unmapped symbol blocks D1 and D2 responsiveto respective streams of data codewords CW1 and CW2 usinginterleaver/modulators IM1 and IM2. For rank 3 transmissions, modulator405 may generate three streams of unmapped symbol blocks D1, D2, and D3responsive to respective streams of data codewords CW1, CW2, and CW3using interleaver/modulators IM1, IM2, and IM3. For rank 4transmissions, modulator 405 may generate four streams of unmappedsymbol blocks D1, D2, D3, and D4 responsive to respective streams ofdata codewords CW1, CW2, CW3, and CW4 using interleaver/modulators IM1,IM2, IM3, and IM4. Modulator 405 may apply modulation orders responsiveto input from adaptive controller 315 determined based on CQI feedbackfrom wireless terminal 200.

In addition, each interleaver/modulator IM1, IM2, IM3, and/or IM4 mayinterleave data of two or more codewords of a stream so that two or moreconsecutive unmapped symbol blocks of a respective stream includesymbols representing data of the two or more consecutive codewords. Forexample, data of consecutive data codewords cw1-1 and cw1-2 of datacodeword stream CW1 may be interleaved and modulated to provideconsecutive unmapped symbol blocks d1-1 and d1-2 of stream D1.Similarly, data of consecutive data codewords cwt-1 and cwt-2 of datacodeword stream CW2 may be interleaved and modulated to provideconsecutive unmapped symbol blocks d2-1 and d2-2 of stream D2; data ofconsecutive data codewords cw3-1 and cw3-2 of data codeword stream CW3may be interleaved and modulated to provide consecutive unmapped symbolblocks d3-1 and d3-2 of stream D3; and/or data of consecutive datacodewords cw4-1 and cw4-2 of data codeword stream CW4 may be interleavedand modulated to provide consecutive unmapped symbol blocks d4-1 andd4-2 of stream D4.

Symbols of streams of unmapped symbol blocks D1, D2, D3, and D4 may bemapped to respective streams of mapped symbol blocks X1, X2, X3, and X4(for respective MIMO transmission layers), as discussed in greaterdetail below. For rank one transmissions, all input data may beprocessed through transport data block generator TB1 to provide a singlestream of transport data blocks B1, the single stream of transport datablocks may be encoded using channel encoder CE1 to provide a singlestream of data codewords CW1, and the single stream of data codewordsmay be interleaved/modulated using interleaver/modulator IM1 to providea single stream of unmapped symbol blocks D1. Symbols of the singlestream of unmapped symbol blocks D1 may be mapped to a single stream ofmapped symbol blocks X1 (including mapped symbol blocks x1-1, x1-2,x1-3, etc.). Each unmapped symbol block d and each mapped symbol blockx, for example, may include M symbols such that each unmapped symbolblock d includes symbols d(i) and each mapped symbol block x includessymbols x(i), where i=1 to M. With rank 1 transmissions, symbols d1-1(i)of unmapped symbol block d1-1 may thus map directly to symbols x1-1(i)of mapped symbol block x1-1, symbols d1-2(i) of unmapped symbol blockd1-2 may map directly to symbols x1-2(i) of mapped symbol block x1-2,symbols d1-3(i) of unmapped symbol block d1-3 may map directly tosymbols x1-3(i) of mapped symbol block x1-3, etc.

Stated in other words, for rank 1 transmissions, x1-j(i)=d1-j(i), wherej identifies the block of the stream of unmapped symbol blocks D1 andmapped symbol blocks X1. With rank one transmissions, only one stream ofunmapped symbol blocks D1 and only one stream of mapped symbol blocks X1may be used for the single layer MIMO transmissions. Spreader/scrambler409 may include a plurality of spreaders/scramblers SS1, SS2, SS3, andSS4, but with only one stream of mapped symbol blocks X1 for one layerMIMO transmission, only one spreader/scrambler SS1 is used tospread/scramble the stream of mapped symbol blocks (e.g., using a Walshcode) to provide a stream of spread symbols blocks Y1 (including spreadsymbol blocks y1-1, y1-2, y1-3, etc.), and layer precoder 411 may applya rank 1 MIMO precoding vector to precode (e.g., to apply precodingweights to) the stream of spread symbol blocks Y1 for transmissionthrough transceiver 109 and antennas Ant-1, Ant-2, Ant-3, and Ant-4 ofantenna array 117.

For rank two transmissions, input data may be processed throughtransport data block generators TB1 and TB2 to provide two streams oftransport data blocks B1 and B2, the two streams of transport datablocks may be encoded using channel encoders CE1 and CE2 (e.g., usingdifferent coding characteristics/rates) to provide two streams of datacodewords CW1 and CW2, and the two streams of codewords may beinterleaved/modulated using interleavers/modulators IM1 and IM2 toprovide two streams of unmapped symbol blocks D1 and D2. Symbols of thetwo streams of unmapped symbol blocks D1 and D2 may be mapped torespective streams of mapped symbol blocks X1 (including mapped symbolblocks x1-1, x1-2, x1-3, etc.) and X2 (including mapped symbol blocksx1-1, x1-2, x1-3, etc.) for respective MIMO transmission layers. Eachunmapped symbol block d of streams D1 and D2 and each mapped symbolblock x of streams X1 and X2, for example, may include M symbols suchthat each unmapped symbol block d includes symbols d(i) and each mappedsymbol block x includes symbols x(i), where i=1 to M. With rank 2transmissions: symbols d1-1(i) of unmapped symbol block d1-1 may mapdirectly to symbols x1-1(i) of mapped symbol block x1-1, and symbolsd2-1(i) of unmapped symbol block d2-1 may map directly to symbolsx2-1(i) of mapped symbol block x2-1; symbols d1-2(i) of unmapped symbolblock d1-2 may map directly to symbols x1-2(i) of mapped symbol blockx1-2, and symbols d2-2(i) of unmapped symbol block d2-2 may map directlyto symbols x2-2(i) of mapped symbol block x2-2; symbols d1-3(i) ofunmapped symbol block d1-3 may map directly to symbols x1-3(i) of mappedsymbol block x1-3, and symbols d2-3(i) of unmapped symbol block d2-3 maymap directly to symbols x2-3(i) of mapped symbol block x2-3; etc.

Stated in other words, for rank 2 transmissions, x1-j(i)=d1-j(i), andx2-j(i)=d2-j(i), where j identifies the block of the stream of unmappedsymbol blocks D1/D2 and mapped symbol blocks X1/X2. With rank twotransmissions, only two streams of unmapped symbol blocks D1 and D2 andonly two streams of mapped symbol blocks X1 and X2 may be used for thetwo layer MIMO transmissions. Spreader/scrambler 409 may include aplurality of spreaders/scramblers SS1, SS2, SS3, and SS4, but with onlytwo streams of mapped symbol blocks X1 and X2, only twospreader/scramblers SS1 and SS2 are used to spread/scramble the twostreams of mapped symbol blocks (e.g., using a Walsh code) to providestreams of spread symbols blocks Y1 (including spread symbol blocksy1-1, y1-2, y1-3, etc.) and Y2 (including spread symbol blocks y2-1,y2-2, y2-3, etc.), and layer precoder 411 may apply a rank 2 MIMOprecoding vector to precode (e.g., to apply precoding weights to) thestreams of spread symbol blocks Y1 and Y2 for transmission throughtransceiver 109 and antennas Ant-1, Ant-2, Ant-3, and Ant-4 of antennaarray 117.

For rank three transmissions, input data may be processed throughtransport data block generators TB1, TB2, and TB3 to provide threestreams of transport data blocks B1, B2, and B3, the three streams oftransport data blocks may be encoded using channel encoders CE1, CE2,and CE3 (e.g., using different coding characteristics/rates) to providethree streams of data codewords CW1, CW2, and CW3, and the three streamsof codewords may be interleaved/modulated using interleavers/modulatorsIM1, IM2, and IM3 to provide three streams of unmapped symbol blocks D1,D2, and D3.

For rank three transmissions (and for rank 4 transmissions) according toembodiments of FIG. 4, layer mapper 407 may include a symbol blockconcatenator 407 a and a layer separator 407 b as shown in FIG. 5.Symbol block concatenator 407 a may concatenate/combine two of the threestreams of unmapped symbol blocks (e.g., streams D2 and D3 of unmappedsymbol blocks, streams D1 and D3 of unmapped symbol blocks, or streamsD1 and D2 of unmapped symbol blocks) to provide one concatenated streamof symbol blocks, and layer separator 407 b may separate symbols of theconcatenated stream of symbol blocks to provide two streams of mappedsymbol blocks (e.g., streams X2 and X3 of mapped symbol blocks, streamsX1 and X3 of mapped symbol blocks, or streams X1 and X2 of mapped symbolblocks). The remaining stream of unmapped symbol blocks (e.g., stream D1of unmapped symbol blocks, stream D2 of unmapped symbol blocks, orstream D3 of unmapped symbol blocks) may be mapped directly to theremaining stream of mapped symbol blocks (e.g., stream X1 of mappedsymbol blocks, stream X2 of mapped symbol blocks, or stream X3 of mappedsymbol blocks). Symbols of two streams of unmapped symbol blocks maythus be concatenated (e.g., combined) and then separated so that symbolsof two streams of mapped symbol blocks are a mixture of symbols from thetwo streams of unmapped symbol blocks, and symbols of the remainingstream of unmapped symbol blocks may be mapped directly to the remainingstream of mapped symbol blocks.

As shown in FIG. 5 by way of example, symbol block concatenator 407 amay provide concatenated outputs C1, C2, C3, C4, C5, and/or C6representing 6 different combinations of streams of unmapped symbolblocks D1, D2, D3, and D4. As noted above, each unmapped symbol block dof streams D1, D2, D3, and D4 may include M symbols such that eachunmapped symbol block d includes symbols d(i), where i=1 to M.Accordingly, each concatenated symbol block C generated by symbol blockconcatenator 407 a may include 2*M symbols int(k) where k=1 to 2*M, asshown below:

For C1, symbols c1-j(k)=d2-j(k), for k=1 to M; and

-   -   symbols c1-j(k)=d3-j(k-M), for k=M+1 to 2M;

For C2, symbols c2-j(k)=d1-j(k), for k=1 to M, and

-   -   symbols c2-j(k)=d3-j(k-M), for k=M+1 to 2M;

For C3, symbols c3-j(k)=d1-j(k), for k=1 to M, and

-   -   symbols c3-j(k)=d2-j(k-M), for k=M+1 to 2M;

For C4, symbols c4-j(k)=d1-j(k), for k=1 to M, and

-   -   symbols c4-j(k)=d4-j(k-M), for k=M+1 to 2M;

For C5, symbols c5-j(k)=d2-j(k), for k=1 to M, and

-   -   symbols c5-j(k)=d4-j(k-M), for k=M+1 to 2M;

For C6, symbols c6-j(k)=d3-j(k), for k=1 to M, and

-   -   symbols c6-j(k)=d4-j(k-M), for k=M+1 to 2M;        Accordingly, concatenated symbol stream C1 represents a        combination of unmapped symbol streams D2 and D3, concatenated        symbol stream C2 represents a combination of unmapped symbol        streams D1 and D3, concatenated symbol stream C3 represents a        combination of unmapped symbol streams D1 and D2, concatenated        symbol stream C4 represents a combination of unmapped symbol        streams D1 and D4, concatenated symbol stream C5 represents a        combination of unmapped symbol streams D2 and D4, and        concatenated symbol stream C6 represents a combination of        unmapped symbol streams D3 and D4. For rank 3 transmissions,        only of one of symbol block concatenator 407 a outputs (e.g.,        C1, C2, or C3) may be used. Operations of layer mapper 407 for        rank three transmission are discussed in greater detail below        with respect to three options.

According to Option 1 for layer mapper 407 for rank three transmissions,symbols of unmapped blocks d1-j from stream D1 map directly to symbolsof mapped blocks x1-j of stream X1, even symbols of concatenator outputblocks c1-j from stream C1 (comprising symbols of streams D2 and D3 ofunmapped symbol blocks) map to symbols of mapped blocks x2-j of streamX2, and odd symbols of concatenator output blocks c1-j from stream C1(comprising symbols of streams D2 and D3 of unmapped symbol blocks) mapto symbols of mapped blocks x3-j of stream X3.

FIGS. 4 and 5, Rank 3, Option 1

x1-j(i)=d1-j(i), for i=1 to M

x2-j(i)=c1-j(2 i), for i=1 to M

x3-j(i)=c1-j(2 i−1), for i=1 to M

Symbols of unmapped streams D2 and D3 may thus be combined/concatenated(e.g., using symbol block concatenator 407 a) and mapped into streams X2and X3 of mapped symbol blocks so that symbol blocks of each of streamsX2 and X3 include symbols of both streams D2 and D3 of unmapped symbolblocks.

According to Option 2 for layer mapper 407 for rank three transmissions,symbols of unmapped blocks d2-j from stream D2 map directly to symbolsof mapped blocks x2-j of stream X2, even symbols of concatenator outputblocks c2-j from stream C2 (comprising symbols of streams D1 and D3 ofunmapped symbol blocks) map to symbols of mapped blocks x1-j of streamX1, and odd symbols of concatenator output blocks c2-j from stream C2(comprising symbols of streams D1 and D3 of unmapped symbol blocks) mapto symbols of mapped blocks x3-j of stream X3.

FIGS. 4 and 5, Rank 3, Option 2

x2-j(i)=d2-j(i), for i=1 to M

x1-j(i)=c2-j(2 i), for i=1 to M

x3-j(i)=c2-j(2 i−1), for i=1 to M

Symbols of unmapped streams D1 and D3 may thus be combined/concatenated(e.g., using symbol block concatenator 407 a) and mapped into mappedstreams X1 and X3 of mapped symbol blocks so that symbol blocks of eachof streams X1 and X3 include symbols of both streams D1 and D3 ofunmapped symbol blocks.

According to Option 3 for layer mapper 407 for rank three transmissions,symbols of unmapped blocks d3-j from stream D3 map directly to symbolsof mapped blocks x3-j of stream X3, even symbols of concatenator outputblocks c3-j from stream C3 (comprising symbols of streams D1 and D2 ofunmapped symbol blocks) map to symbols of mapped blocks x1-j of streamX1, and odd symbols of concatenator output blocks c3-j from stream C3(comprising symbols of streams D1 and D2 of unmapped symbol blocks) mapto symbols of mapped blocks x3-j of stream X3.

FIGS. 4 and 5, Rank 3, Option 3

x3-j(i)=d3-j(i), for i=1 to M

x1-j(i)=c3-j(2 i), for i=1 to M

x2-j(i)=c3-j(2 i−1), for i=1 to M

Symbols of unmapped streams D1 and D2 may thus be combined/concatenated(e.g., using symbol block concatenator 407 a) and mapped to mappedstreams X1 and X2 of mapped symbol blocks, so that symbol blocks of eachof streams X1 and X2 include symbols of both streams D1 and D2 ofunmapped symbol blocks.

With rank three transmissions, one stream of unmapped symbol blocks ismapped directly to one stream of mapped symbol blocks, and two unmappedsymbol blocks are combined/concatenated and separated into the other twostreams of mapped symbol blocks. Spreader/scrambler 409 may include aplurality of spreaders/scramblers SS1, SS2, SS3, and SS4, but with onlythree streams of mapped symbol blocks X1, X2, and X3, only threespreader/scramblers SS1, SS2, and SS3 are used to spread/scramble thethree streams of mapped symbol blocks (e.g., using a Walsh code) toprovide streams of spread symbols blocks Y1 (including spread symbolblocks y1-1, y1-2, y1-3, etc.), Y2 (including spread symbol blocks y2-1,y2-2, y2-3, etc.), and Y3 (including spread symbol blocks y3-1, y3-2,y3-3, etc.). Layer precoder 411 may apply a rank 3 MIMO precoding vectorto precode (e.g., to apply precoding weights to) the streams of spreadsymbol blocks Y1, Y2, and Y3 for transmission through transceiver 109and antennas Ant-1, Ant-2, Ant-3, and Ant-4 of antenna array 117. Withrank 3 transmissions, concatenator outputs C4, C5, and C6 may beunused/unnecessary.

For rank four transmissions, input data may be processed throughtransport data block generators TB1, TB2, TB3, and TB4 to provide fourstreams of transport data blocks B1, B2, B3, and B4, the four streams oftransport data blocks may be encoded using channel encoders CE1, CE2,CE3, and CE4 (e.g., using different coding characteristics/rates) toprovide four streams of data codewords CW1, CW2, CW3, and CW4, and thefour streams of codewords may be interleaved/modulated usinginterleavers/modulators IM1, IM2, IM3, and IM4 to provide four streamsof unmapped symbol blocks D1, D2, D3, and D4. For rank fourtransmissions according to embodiments of FIG. 4, layer mapper 407 mayinclude a symbol block concatenator 407 a and a layer separator 407 bproviding concatenated symbol streams (e.g., C1, C2, C3, C4, C5, and/orC6) as discussed above with respect to FIG. 5. Operations of layermapper 407 for rank three transmission are discussed in greater detailbelow with respect to three options.

According to Option 1 for layer mapper 407 for rank four transmissions,even symbols of concatenator output blocks c2-j from stream C2(comprising symbols of streams D1 and D3 of unmapped symbol blocks) mapto symbols of mapped blocks x1-j of stream X1, and odd symbols ofconcatenator output blocks c2-j from stream C2 map to symbols of mappedblocks x3-j of stream X3. In addition, even symbols of concatenatoroutput blocks c5-j from stream C5 (comprising symbols of streams D2 andD4 of unmapped symbol blocks) map to symbols of mapped blocks x2-j ofstream X2, and odd symbols of concatenator output blocks c5-j fromstream C5 map to symbols of mapped blocks x4-j of stream X4.

FIGS. 4 and 5, Rank 4, Option 1

x1-j(i)=c2-j(2 i), for i=1 to M

x3-j(i)=c2-j(2 i−1), for i=1 to M

x2-j(i)=c5-j(2 i), for i=1 to M

x4-j(i)=c5-j(2 i−1), for i=1 to M

Symbols of unmapped streams D1 and D3 may thus be combined/concatenated(e.g., using symbol block concatenator 407 a) and mapped into streams X1and X3 of mapped symbol blocks so that symbol blocks of each of streamsX1 and X3 include symbols of both streams D1 and D3 of unmapped symbolblocks. Similarly, symbols of unmapped streams D2 and D4 may thus becombined/concatenated (e.g., using symbol block concatenator 407 a) andmapped into streams X2 and X4 of mapped symbol blocks so that symbolblocks of each of streams X2 and X4 include symbols of both streams D2and D4 of unmapped symbol blocks.

According to Option 2 for layer mapper 407 for rank four transmissions,even symbols of concatenator output blocks c4-j from stream C4(comprising symbols of streams D1 and D4 of unmapped symbol blocks) mapto symbols of mapped blocks x1-j of stream X1, and odd symbols ofconcatenator output blocks c4-j from stream C4 map to symbols of mappedblocks x4-j of stream X4. In addition, even symbols of concatenatoroutput blocks c1-j from stream C1 (comprising symbols of streams D2 andD3 of unmapped symbol blocks) map to symbols of mapped blocks x2-j ofstream X2, and odd symbols of concatenator output blocks c1-j fromstream C1 map to symbols of mapped blocks x3-j of stream X3.

FIGS. 4 and 5, Rank 4, Option 2

x1-j(i)=c4-j(2 i), for i=1 to M

x4-j(i)=c4-j(2 i−1), for i=1 to M

x2-j(i)=c1-j(2 i), for i=1 to M

x3-j(i)=c1-j(2 i−1), for i=1 to M

Symbols of unmapped streams D1 and D4 may thus be combined/concatenated(e.g., using symbol block concatenator 407 a) and mapped into streams X1and X4 of mapped symbol blocks so that symbol blocks of each of streamsX1 and X4 include symbols of both streams D1 and D4 of unmapped symbolblocks. Similarly, symbols of unmapped streams D2 and D3 may thus becombined/concatenated (e.g., using symbol block concatenator 407 a) andmapped into streams X2 and X3 of mapped symbol blocks so that symbolblocks of each of streams X2 and X3 include symbols of both streams D2and D3 of unmapped symbol blocks.

According to Option 3 for layer mapper 407 for rank four transmissions,even symbols of concatenator output blocks c3-j from stream C3(comprising symbols of streams D1 and D2 of unmapped symbol blocks) mapto symbols of mapped blocks x1-j of stream X1, and odd symbols ofconcatenator output blocks c3-j from stream C3 map to symbols of mappedblocks x2-j of stream X2. In addition, even symbols of concatenatoroutput blocks c6-j from stream C6 (comprising symbols of streams D3 andD4 of unmapped symbol blocks) map to symbols of mapped blocks x3-j ofstream X3, and odd symbols of concatenator output blocks c6-j fromstream C6 map to symbols of mapped blocks x4-j of stream X4.

FIGS. 4 and 5, Rank 4, Option 3

x1-j(i)=c3-j(2 i), for i=1 to M

x2-j(i)=c3-j(2 i−1), for i=1 to M

x3-j(i)=c6-j(2 i), for i=1 to M

x4-j(i)=c6-j(2 i−1), for i=1 to M

Symbols of unmapped streams D1 and D2 may thus be combined/concatenated(e.g., using symbol block concatenator 407 a) and mapped into streams X1and X2 of mapped symbol blocks so that symbol blocks of each of streamsX1 and X2 include symbols of both streams D1 and D2 of unmapped symbolblocks. Similarly, symbols of unmapped streams D3 and D4 may thus becombined/concatenated (e.g., using symbol block concatenator 407 a) andmapped into streams X3 and X4 of mapped symbol blocks so that symbolblocks of each of streams X3 and X4 include symbols of both streams D3and D4 of unmapped symbol blocks.

With rank four transmissions, a first pair of streams of unmapped symbolblocks are combined/concatenated and separated into a first pair ofmapped symbol blocks, and a second pair of streams of unmapped symbolblocks are combined/concatenated and separated into a second pair ofmapped symbol blocks. Spreader/scrambler 409 may include a plurality ofspreaders/scramblers SS1, SS2, SS3, and SS4, and with four streams ofmapped symbol blocks X1, X2, X3, and X4, all four spreader/scramblersSS1, SS2, SS3, and SS4 may be used to spread/scramble the four streamsof mapped symbol blocks (e.g., using a Walsh code) to provide streams ofspread symbols blocks Y1 (including spread symbol blocks y1-1, y1-2,y1-3, etc.), Y2 (including spread symbol blocks y2-1, y2-2, y2-3, etc.),Y3 (including spread symbol blocks y3-1, y3-2, y3-3, etc.), and Y4(including spread symbol blocks y4-1, y4-2, y4-3, etc.). Layer precoder411 may apply a rank 4 MIMO precoding vector to precode (e.g., to applyprecoding weights to) the streams of spread symbol blocks Y1, Y2, Y3,and Y4 for transmission through transceiver 109 and antennas Ant-1,Ant-2, Ant-3, and Ant-4 of antenna array 117.

According to some embodiments of FIGS. 4 and 5, layer mapper 407 mayapply fixed mapping functions (known to both base station 100 andwireless terminal 200) for rank 3 and rank 4 transmissions. For Rank 3transmission, for example, layer mapper 407 may always use the rank 3option 1, and for Rank 4 transmission, layer mapper 407 may always usethe rank 4 option 1 mapping. Using fixed mappings may reduce controlchannel traffic that may otherwise be needed to signal mappingselections/recommendations between base station 100 and wirelessterminal 200.

According to some other embodiments of FIG. 4, mapping functions forrank 3 and rank 4 transmissions may be dynamically selected. Wirelessterminal processor 201, for example, may select from a plurality ofmapping function options (e.g., one of options 1-3 for rank 3 or one ofoptions 1-3 for rank 4 as discussed above), and this selection may beidentified in CQI feedback that is transmitted to base station 100 for asubsequent downlink transmission. More particularly, a rank selectionmay be included in the CQI feedback, and an additional 2 bit code may beused to identify one of options 1-3 for rank 3 transmissions or one ofoptions 1-3 for rank 4 transmissions. Wireless terminal processor 201may thus chose a mapping option to increase a quality and/or rate ofdata transmission over the downlink. According to other embodiments,adaptive controller 415 may select the mapping option for rank 3 andrank 4 transmissions, and the selection may be signaled to wirelessterminal 200.

At wireless terminal 200, operations of processor 201 may mirroroperations of base station processor 101 when receiving the MIMOdownlink communications transmitted by the base station. Moreparticularly, elements/functionalities of wireless terminal processor201 are illustrated in FIG. 6 mirroring elements/functionalities of basestation processor 101 discussed above with reference to FIGS. 4 and 5.

Radio signals may be received through MIMO antenna elements of MIMOantenna array 217 and transceiver 209, and the radio signals may bedecoded by layer decoder 601 using a MIMO decoding vector to generate aplurality of MIMO decoded symbol layers X1′, X2′, X3′, and/or X4′depending on MIMO rank used for transmission/reception. Layer Decoder601 may use a decoding vector corresponding to the precoding vector usedby base station 100. Layer decoder 601 may generate a single decodedsymbol layer X1′ for rank 1 reception, layer decoder 601 may generatetwo decoded symbol layers X1′ and X2′ for rank 2 reception, layerdecoder 601 may generate three decoded symbol layers X1′, X2′, and X3′for rank 3 reception, and layer decoder 601 may generate four decodedsymbol layers X1′, X2′, X3′, and X4′ for rank 4 transmission.

For rank one reception, layer demapper 603 may demap symbols of decodedsymbol layer X1′ blocks x1′-j directly to symbols of unmapped symbollayer D1′ blocks d1′-j, demodulator/deinterleaver DM-1 maydemodulate/deinterleave unmapped symbol layer blocks d1′-j to providedata codewords cw1′-j of data codeword stream CW1′, and channel decoderCD1 may decode data codewords cw1′-j of data codeword stream CW1′ toprovide transport blocks b1′-j of stream B1′. Transport block generator607 may then pass transport blocks b1′-j of stream B1′ as a data stream.During rank one reception, functionality of demodulators/deinterleaversDM2, DM3, and DM4 and channel decoders CD2, CD3, and CD4 may be unused.

For rank two reception, layer decoder 601 may generate decoded symbollayers X1′ and X2′. Layer demapper 603 may demap symbols of decodedsymbol layer X1′ blocks x1′-j directly to symbols of unmapped symbollayer D1′ blocks d1′-j, and layer demapper 603 may demap symbols ofdecoded symbol layer X2′ blocks x2′-j directly to symbols of unmappedsymbol layer D2′ blocks d2′-j. Demodulator/deinterleaver DM-1 maydemodulate/deinterleave unmapped symbol layer blocks d1′-j to providedata codewords cw1′-j of data codeword stream CW1′, anddemodulator/deinterleaver DM-2 may demodulate/deinterleave unmappedsymbol layer blocks d2′-j to provide data codewords cw2′-j of datacodeword stream CW2′. Channel decoder CD1 may decode data codewordscw1′-j of data codeword stream CW1′ to provide transport blocks b1′-j ofstream B1′, and channel decoder CD2 may decode data codewords cw2′-j ofdata codeword stream CW2′ to provide transport blocks b1′-j of streamB2′. Transport block generator 607 may then combine transport blocksb1′-j and b2′-j of streams B1′ and B2′ as a data stream. During rank tworeception, functionality of demodulators/deinterleavers DM3 and DM4 andchannel decoders CD3 and CD4 may be unused.

During higher rank reception (e.g., rank 3 and/or rank 4 reception),layer demapper 603 may demap symbols of the first and second decodedsymbol blocks x1′-1 and x2′-1 of respective decoded symbol block streamsX1′ and X2′ so that an unmapped symbol block d1′-1 of stream D1′includes some symbols of decoded symbol blocks x1′-1 and x2′-1 and sothat an unmapped symbol block d2′-1 of stream D2′ includes other symbolsof decoded symbol blocks x1′-1 and x2′-1. Moreover, the first and seconddecoded symbol blocks x1′-1 and x2′-2 may represent data received duringa same TFRE. The unmapped symbol blocks d1′-1 and d2′-2 of streams D1′and D2′ may be demodulated/deinterleaved using respectivedemodulators/deinterleavers DM1 and DM2 to provide respective datacodewords cw1′-1 and cw1′-2. Channel decoders CD1 and CD2 may thendecode the respective data codewords cw1′-1 and cw2′-2 of streams CW1′and CW2′ using different channel code characteristics (e.g., differentcode rates) to generate respective data blocks b1′-1 and b2′-1 ofstreams B1′ and B2′. Transport block generator 607 may then combinetransport blocks b1′-j and b2′-j of streams B1′ and B2′ as a datastream.

During rank 3 reception, a third stream X3′ of decoded symbol blocks maybe generated by layer decoder 601 (in addition to streams X1′ and X2′)and demapped directly by layer demapper 603 to stream D3′ of unmappedsymbol blocks. The stream D3′ of unmapped symbol blocks may be processedthrough demodulator/deinterleaver DM3 and channel decoder CD3, and theresulting stream B3′ of transport blocks may be combined with streamsB1′ and B2′ by transport block combiner 607. During rank 4 reception,third and fourth streams X3′ and X4′ of decoded symbol blocks may begenerated by layer decoder 601 (in addition to streams X1′ and X2′).Layer demapper 603 may demap symbol blocks of streams X3′ and X4′ sothat symbol blocks of D3′ include symbols from symbol blocks of streamsX3′ and X4′ and so that symbol blocks of D4′ include symbols from symbolblocks of streams X3′ and X4′. The streams D3′ and D4′ of unmappedsymbol blocks may be processed through demodulators/deinterleavers DM3and DM4 and channel decoders CD3 and CD4, and the resulting streams B3′and B4′ of transport blocks may be combined with streams B1′ and B2′ bytransport block combiner 607.

As 4-branch MIMO transmission for HSDPA is standardized in 3GPP(RP-111393, Four Branch MIMO transmission for HSDPA, 3GPP TSG-RANmeeting #53, Fukuoka, Japan, Sep. 13 to 16, 2011), maintaining backwardscompatibility and reducing/minimizing impact on the specification aretwo goals during the standardization process. For example, reusingexisting functionality or using existing functionality with minorupdates is generally preferred relative to a completely new solution.

When introducing 4-branch MIMO, up to 4 layers (or streams) can betransmitted simultaneous using the same physical resource (i.e. time,frequency and codes). Accordingly, up to 4 data blocks (so calledtransport blocks or TBs) and associated control signaling may betransmitted per TTI (transmission time interval).

Associated control overhead may be considered as too large to be aviable solution. Hence, a solution based on mapping pairs of TBs(transport blocks) to a (so called) codeword (CW) has been discussed in3GPP (R1-114366, Summary of 4-branch MIMO for HSPA session, 3GPP TSG RANWG1 Meeting #67, San Francisco, Calif. USA, 14 to 18 Nov. 2011). Here,two equal size TBs are mapped to one CW, and associated controlsignaling can then relate to a CW instead of to transport blocks. Thisis sometimes referred to as “TB bundling” (U.S. patent application Ser.No. 13/255,322 entitled “Methods And Entities For Modulation SymbolTransport” and filed Sep. 8, 2011). This may limit, for example, theHARQ (hybrid automatic repeat request) related signaling to a maximum oftwo ACK/NACKs (Acknowledge/Negative-Acknowledge messages). Since the twoTBs associated with one CW are of equal size, only parameters for one ofthem is needed, and hence the DL (downlink) signaling overhead can bereduced/minimized. Since a maximum of two CWs are possible, solutionsfrom 2-branch HSDPA MIMO may be reused. Hence, impact on thespecification may be reduced/minimized.

Wireless terminal processor 201 and/or transceiver 209 maydefine/configure/provide operations/functionality of a plurality ofreception layers/streams as discussed above with respect to FIG. 6: witha first layer RL1 (e.g., including DM1 and CD1) being used for MIMOranks 1, 2, 3, and 4; with a second layer RL2 (e.g., including DM2 andCD2) being used for MIMO ranks 2, 3, and 4; with a third layer RL3(e.g., including DM3 and CD3) being used for MIMO ranks 3 and 4; andwith a fourth MIMO layer RL4 (e.g., including DM4 and CD4) being usedfor MIMO rank 4. Separate decoding (e.g., using decoder functionallyillustrated by decoders CD1-4 of FIG. 6) may be performed for each MIMOlayer received during a MIMO TTI. Wireless terminal processor 201 and/ortransceiver 209, for example, may define, configure, and/or provide oneor more of reception layers RL1, RL2, RL3, and/or RL4 for a givenTTI/TFRE responsive to rank and/or precoding vector information providedfrom base station 100 via downlink signaling. For example, a higher MIMOrank (defining a respective higher number of reception layers/streams)may be selected when the wireless terminal detects that the downlinkchannel has a higher SINR (e.g., when the wireless terminal isrelatively close to the base station), and a lower MIMO rank (defining arespective lower number of reception layers/streams) may be selectedwhen the wireless terminal detects that the downlink channel has a lowerSINR (e.g., when the wireless terminal is relatively distant from thebase station).

While separate transport block generator, encoder, modulator, layermapper, spreader/scrambler, and layer precoder blocks are illustrated inFIG. 4 by way of example, the blocks of FIG. 4 merely illustratefunctionalities/operations of base station processor 101 and/ortransceiver 109. Sub-blocks (e.g., transport blocks TB1-TB4, channelencoders CE1-CE4, interleavers/modulators IM1-IM4, and/or spreaderscramblers SS1-SS4) of FIG. 4 further illustratefunctionalities/operations of transport block generator, encoder block,modulator block, and/or spreader/scrambler block supporting transmissionlayers TL1-TL4. Processor 101 and/or transceiver 109, however, mayprovide/define/configure functionality/operations of only onetransmission layer TL1 (e.g., including TB1, CE1, and IM1) during rank 1transmission; processor 101 and/or transceiver 209 mayprovide/define/configure functionality/operations of only twotransmission layers TL1 and TL2 (e.g., including TB2, CE2, and IM2)during rank 2 transmission; processor 101 and/or transceiver 209 mayprovide/define/configure functionality/operations of only 3 transmissionlayers TL1, TL2, and TL3 (e.g., using TB3, CE3, and IM3) during rank 3transmission; and processor 101 and/or transceiver 109 mayprovide/define/configure functionality/operations of four transmissionlayers TL1, TL2, TL3, and TL4 (e.g., using TB4, CE4, and IM4) onlyduring rank 4 transmission. When multiple transmission layers areprovided/defined/configured for a TTI/TFRE, for example, processor 101and/or transceiver 109 may provide/define/configurefunctionality/operations of multiple transport block sub-blocks,multiple channel decoder sub-blocks, multiple interleaver/modulatorsub-blocks, and/or multiple spreader/scrambler sub-blocks to allowparallel processing of data of different transmission layers beforetransmission during a TTI/TFRE, or processor 101 and/or transceiver 109may provide/define/configure functionality/operations of a singletransport block, a single channel encoder, a singleinterleaver/modulator, and/or a single spreader scrambler to allowserial processing of data of different transmission layers beforetransmission during a TTI/TFRE.

While separate layer decoder, layer demapper, demodulator/deinterleaver,channel decoder, and transport block combiner blocks/sub-blocks areillustrated in FIG. 6 by way of example, the blocks of FIG. 6 merelyillustrate functionalities/operations of wireless terminal processor 201and/or transceiver 209. For example, sub-blocks (e.g.,demodulator/deinterleaver DM1-DM4 and channel decoders CD1-CD4) of FIG.6 illustrate functionalities/operations providing reception layer RL1(e.g., including DM1 and CD1), reception layer RL2 (e.g., including DM2and CD2), reception layer RL3 (e.g., including DM3 and CD3), andreception layer RL4 (e.g., including DM4 an CD4). Processor 201 and/ortransceiver 209, however, may provide/define/configurefunctionality/operations of only one reception layer RL1 during rank 1reception; processor 201 and/or transceiver 201 mayprovide/define/configure functionality/operations of only two receptionlayers RL1 and RL2 during rank 2 transmission; processor 201 and/ortransceiver 209 may provide/define/configure functionality/operations ofonly 3 reception layers RL1, RL2, and RL3 during rank 3 transmission;and processor 201 and/or transceiver 209 may provide/configure/definefunctionality/operations of four reception layers RL1, RL2, RL3, and RL4only during rank 4 transmission. When multiple reception layers areprovided/defined/configured, for example, processor 201 and/ortransceiver 209 may provide/define/configure functionality/operations ofmultiple demodulator/deinterleaver blocks and/or multiple channeldecoder blocks to allow parallel processing of data of differentreception layers during a TTI/TFRE, or processor 201 and/or transceiver209 may provide/define/configure functionality/operations of a singledemodulator/deinterleaver block and/or a single channel decoder to allowserial processing of data of different reception layers during aTTI/TFRE.

In FIG. 7, an outline of the transmitter chain is shown. Here two TBsare mapped to one CW “TB2CW.” Note that the case is shown when two CWsare mapped to each codeword. In the case of a single layer transmission(i.e. rank-1), one TB will be mapped to a single CW. Similarly, for arank-3 transmission, one TB will be mapped to one of the CWs while twoTBs are mapped to the other CW.

The codewords are then mapped to layers. Here several possibilities mayexist, but a fixed mapping (see also, LTE 36.211, Section 6.3.3.2 andFIG. 2) is assumed here for simplicity. The number of layers wouldcorrespond to the “rank” of the transmission. Finally the layers aremapped to the antenna domain by the spatial precoder. Note that also forlower rank transmissions it may be beneficial to transmit on allantennas. The exact precoder may not be important here, but it isassumed that codebook based precoding is used, at least for CSI (channelstate information) reporting.

In the case where a codeword is mapped to two layers, it may bebeneficial if the two layers have similar quality, because the TB mappedto one CW should be described by a common set of parameters (i.e. thesame TBS or transport block size and the same MCS or modulation andcoding scheme). For example, looking at FIG. 8C (Rank 3), layers 1 and 2should be of similar quality (e.g., a same/similar TBS and/or MCS),while layer 3 can have a very different quality (e.g., a difference TBSand/or MCS) since a CW with other MCS (modulation and coding scheme)parameters is mapped to this layer. Since the CQI (channel qualityindicator) is reported per CW, the individual layer quality may not beknown at the base station, and hence has to be signaled from the UE(user equipment, also referred to as a wireless terminal).

In principle, this can be done in many ways. For example, the UE mayorder the layers by quality.

Ways for the system to make the layer qualities available to the basestation are discussed in greater detail below. Related problems arediscussed above with respect to FIGS. 1-6.

FIG. 9 shows an example of distributing layer quality. Since one CW ismapped to two layers, it may be beneficial if these two layers havesimilar quality (e.g., the same/similar TBS and/or MCS). If a fixedmapping as in FIGS. 8A-D is used, layers one and two are mapped to thesame CW, which may be non-optimal since the layer qualities of theselayers are fairly different. A better mapping, in this example, may beto map layers 1 and 3 to one CW, and to map layers 2 and 4 to the otherCW. To achieve this, some additional signaling may be needed. Thissignaling can be explicit, or implicit as shown below.

Since the layers are defined by the columns of the spatial precodermatrix, one way to address issues noted above may be to includepermutations of the same precoder matrix into the codebook as describedin the following example.

Assume that the layers are defined by the vectors W1=[w1, w2, w3, w4].If several column permutations of this matrix exist in the codebook, theUE can report the precoder matrix matching the fixed CW2L mapping ofFIGS. 8A-D. In this particular example, the 6 permutations W2=[w1, w2,w4, w3], W3=[w1, w3, w2, w4], W4=[w1, w3, w4, w2], W5=[w1, w4, w2, w3]and W6=[w1, w4, w3, w2] would exist. To match the CW2L mapping, theexample in FIG. 9 would then correspond to the permutation W3, sincethis would group layers with similar quality to the same CW. In a rank=3situation, only 2 possibilities may exist [w1, w2, w3] and [w1, w3, w2].

A potential gain with this type of signaling is simplicity. The UE willtry all different precoders (including its permutations) and then reportthe precoder index best fitting to the fixed layer mapping. A potentialdrawback is that the precoder codebook will grow, especially for higherranks where many permutations exist. It may be possible to excludecertain permutations from the codebook and hence reduce its size. Inthis case a certain performance penalty may be expected.

An alternative way to signal the layer order (or rather how to group thelayers) in the case when a CW is mapped to several layers, an explicitsignaling may be used. Here the spatial precoder codebook may includeits base matrices (no permutations), but an additional signaling isintroduced to group the layers. Continuing with the example of FIG. 9where layers 1 and 3 are grouped to one CW, and layers 2 and 4 aregrouped to the other CW, a convention that layer 1 always belongs to CW1may be introduced. Accordingly, an identification of the other layerthat should also belong to CW1 may need to be signaled. In the case ofrank 4 (e.g. this example), there are 3 possibilities and hence 2 bitsmay be used to signal this. In fact, only 1.5 bits may actually beneeded for this signaling, and if this signaling is part of any othersignaling, one bit may be saved compared to explicit signaling. Forexample, there might be another parameter with, for example, 5alternatives, and hence the two parameters may be reported togetherusing 3 bits (8 possibilities).

For a rank=3 situation, only two possibilities may exist. According toFIGS. 8A-D, the UE may need to report which of layers 2 and 3 should bemapped to CW1 together with layer 1.

A third alternative would be to have a flexible CW2L mapping similar tothat described above with respect to FIGS. 1-6. In this case, there isno fixed CW2L mapping as in FIGS. 8A-D, rather the UE would calculatethe throughput (or any related measure) for all combinations and thenreport the “best”. That is, the UE may calculate how to best map severallayers onto 2 CWs for each entry in the precoder codebook.

A potential advantage with the signaling described with respect to FIGS.7-9 would be that the base station can map data to each CW in animproved/optimal way. For example, if the layer qualities are given byFIG. 9, the system will allocate a data rate to CW1 matching the meanquality of layer 1 and layer 2 (and the system will allocate a data rateto CW2 matching a mean quality of layer 3 and layer 4). On the otherhand, if this signaling or ordering is present, the system can allocatea data rate matching the mean of layers 1 and 3 to CW1 and layers 2 and4 to CW2. In this case, the mean of the ordered layers may be higherthan that of layers that are unordered, hence a higher throughput may beexpected.

A potential advantage with the first alternative may be its simplicity.The spatial codebook is expanded and the layer quality ordering isimplicitly signaled with the codebook entry.

A potential advantage with the second alternative may be the possibilityto save on signaling overhead. In the first case, the codebook isexpanded, hence requiring more bits. If the codebook has a fixed sizeper rank (as in LTE), this overhead will be present also for lower rankswhen the ordering is not needed. In the second alternative, the orderingis signaled explicitly and hence can be made rank dependent.

FIGS. 10 and 11A-D are flow charts illustrating operations of basestation 100 discussed above with respect to FIGS. 2 and 4. When data isavailable for transmission/retransmission to wireless terminal 200 atblock 1011, base station 100 may select one or more transmissioncharacteristics such as a rank (RI), a precoding vector (PCI), amodulation and coding scheme (MCS), transport block size (TBS), etc. fortransmission at block 1013, and base station 100 may transmit anidentification(s)/indication(s) of the selected transmissioncharacteristics (e.g., rank, precoding vector, MCS, TBS, etc.) to thewireless terminal. Based on the rank selected at blocks 1013 and 1015for a given TFRE/TTI, operations of FIG. 11A may be performed for rank 1for the given TFRE/TTI as indicated at block 1017, operations of FIG.11B may be performed for rank 2 for the given TFRE/TTI as indicated atblock 1019, operations of FIG. 11C may be performed for rank 3 for thegiven TFRE/TTI as indicated at block 1021, or operations of FIG. 11D maybe performed for rank 4 for the given TFRE/TTI as indicated at block1023.

If rank 1 transmission is selected for the TFRE/TTI at blocks 1013,1015, and 1017 of FIG. 10, base station 100 may proceed with operationsof FIG. 11A. For example, transport block generator 401 may provide theinput data for transmission to the wireless terminal (200) at block1101, and arrange the input data as a data block at block 1102. At block1103, encoder 403 may encode the data block to generate a data codeword,and at block 1104, modulator 405 may modulate the data codeword togenerate symbols of an unmapped symbol block. At block 1105, layermapper 407 may map symbols of the unmapped symbol block to a mappedsymbol block; at block 1106, spreader/scrambler 409 and/or layerprecoder 411 may precode symbols of the mapped symbol block to the rank1 MIMO layer/stream; and at block 1107, the rank 1 MIMO layer/stream maybe transmitted over wireless channel 300 to wireless terminal 200.

When data is available for transmission/retransmission to wirelessterminal 200 for a next TFRE/TTI at block 1108, base station 100 mayselect a rank, a precoding vector, a modulation and coding scheme, atransport block size, etc. for transmission at block 1109, and basestation 100 may transmit identification(s)/indication(s) of the selectedtransmission characteristics (e.g., rank, precoding vector, MCS, TBS,etc.) to the wireless terminal. If rank 1 is maintained at block 1110,operations of blocks 1101-1110 may be repeated for each rank 1 TFRE/TTI.If a different rank (e.g., rank 2, 3, or 4) is selected at blocks 1109and 1110, base station processor 101 may return to block 1015 of FIG. 10as indicated by block 1111.

If rank 2 transmission is selected for the TFRE/TTI at blocks 1013,1015, and 1019 of FIG. 10, base station 100 may proceed with operationsof FIG. 11B. For example, transport block generator 401 may provide theinput data for transmission to the wireless terminal (200) at block1121, and separate the input data into first and second data blocks forthe TFRE/TTI at block 1122. At block 1123, encoder 403 may encode thefirst and second data blocks to generate respective first and seconddata codewords, and at block 1124, modulator 405 may modulate the firstand second data codewords to generate symbols of respective first andsecond unmapped symbol blocks. At block 1125, layer mapper 407 may mapsymbols of the first and second unmapped symbol blocks to respectivefirst and second mapped symbol blocks; at block 1126 a,spreader/scrambler 409 and/or layer precoder 411 may precode symbols ofthe mapped symbol block to a first rank 2 MIMO layer/stream; and atblock 1126 b, spreader/scrambler 409 and/or layer precoder 411 mayprecode symbols of the mapped symbol block to a second rank 2 MIMOlayer/stream. At block 1127, the first and second rank 2 MIMOlayers/streams may be transmitted over wireless channel 300 to wirelessterminal 200.

When data is available for transmission/retransmission to wirelessterminal 200 for a next TFRE/TTI at block 1128, base station 100 mayselect a rank, a precoding vector, a modulation and coding scheme, atransport block size, etc. for transmission at block 1129, and basestation 100 may transmit identification(s)/indication(s) of the selectedtransmission characteristics (e.g., rank, precoding vector, MCS, TBS,etc.) to the wireless terminal. If rank 2 is maintained at block 1130,operations of blocks 1121-1130 may be repeated for each rank 2 TFRE/TTI.If a different rank (e.g., rank 1, 3, or 4) is selected at blocks 1129and 1130, base station processor 101 may return to block 1015 of FIG. 10as indicated by block 1131.

If rank 3 transmission is selected for the TFRE/TTI at blocks 1013,1015, and/or 1019 of FIG. 10, base station 100 may proceed withoperations of FIG. 11C. For example, transport block generator 401 mayprovide input data for transmission to the wireless terminal 200 atblock 1141, and separate the input data into first, second, and thirddata blocks at block 1142. At block 1143, encoder 403 may encode thefirst, second, and third data blocks at block 1143 to generaterespective first, second, and third data codewords; and at block 1144,modulator 405 may modulate data of the first, second, and third datacodewords to provide symbols of respective first, second, and thirdunmapped symbol blocks. As discussed in greater detail below regardingsome embodiments, a mapping selection may be received from wirelessterminal 200 at block 1140 with the mapping selection defining a mappingof symbols from unmapped symbol blocks to mapped symbol blocks.According to some other embodiments, a mapping of symbols from unmappedsymbol blocks may be fixed, or one of a plurality of mapping selectionsmay be selected by base station without receiving input from wirelessterminal 200.

In accordance with Rank 3, Option 1 (discussed above with respect toFIGS. 4 and 5 and shown in FIG. 11C), layer mapper 407 may map symbolsdirectly from the first unmapped symbol block to a first mapped symbolblock at block 1145 a; layer mapper 407 may map symbols from the secondunmapped symbol block to second and third mapped symbol blocks at block1145 b; and layer mapper 407 may map symbols from the third unmappedsymbol block to the second and third mapped symbol blocks at block 1145c. Accordingly, the first mapped symbol block may include symbols of thefirst unmapped symbol block and may exclude symbols of any otherunmapped symbol blocks (other than the first unmapped symbol block); thesecond mapped symbol block may include symbols of the second and thirdunmapped symbol blocks; and the third mapped symbol block may includesymbols of the second and third unmapped symbol blocks. For example, allsymbols of the first unmapped symbol block may map directly to the firstmapped symbol block, even symbols of the second and third unmappedsymbol blocks may map to the second mapped symbol block, and odd symbolsof the second and third unmapped symbol blocks may map to the secondmapped symbol block.

In accordance with Rank 3, Option 2 (discussed above with respect toFIGS. 4 and 5 and shown in FIG. 14A), layer mapper 407 may map symbolsfrom the first unmapped symbol block to first and third mapped symbolblocks at block 1145 a′; layer mapper may directly map symbols from thesecond unmapped symbol block to a second mapped symbol block at block1145 b′; and layer mapper 407 may map symbols from the third unmappedsymbol block to the first and third mapped symbol blocks at block 1145c′. Accordingly, the first mapped symbol block may include symbols ofthe first and third unmapped symbol blocks; the second mapped symbolblock may include symbols of the second unmapped symbol block and mayexclude symbols of any other unmapped symbol block (other than thesecond unmapped symbol block); and the third mapped symbol block mayinclude symbols of the first and third unmapped symbol blocks. Forexample, even symbols of the first and third unmapped symbol blocks maymap to the first mapped symbol block, all symbols of the second unmappedsymbol block may map directly to the second mapped symbol block, and oddsymbols of the first and third unmapped symbol blocks may map to thethird mapped symbol block.

In accordance with Rank 3, Option 3 (discussed above with respect toFIGS. 4 and 5 and shown in FIG. 14B), layer mapper 407 may map symbolsfrom the first unmapped symbol block to first and second mapped symbolblocks at block 1145 a″; layer mapper 407 may map symbols from thesecond unmapped symbol block to the first and second mapped symbolblocks at block 1145 b″; and layer mapper 407 may directly map symbolsfrom the third unmapped symbol block to the third mapped symbol blocksat block 1145 c′. Accordingly, the first mapped symbol block may includesymbols of the first and second unmapped symbol blocks; the secondmapped symbol block may include symbols of the first and second unmappedsymbol blocks; and the third mapped symbol block may include symbols ofthe third unmapped symbol block and may exclude symbols of any otherunmapped symbol block (other than the third unmapped symbol block). Forexample, even symbols of the first and second unmapped symbol blocks maymap to the first mapped symbol block, odd symbols of the first andsecond unmapped symbol block may map to the second mapped symbol block,and all symbols of the third unmapped symbol blocks may map directly tothe third mapped symbol block.

Operations 1145 a′, 1145 b′ and 1145 c′ of FIG. 14A may be substitutedfor operations 1145 a, 1145 b, and 1145 c of FIG. 11C, or operations1145 a″, 1145 b″ and 1145 c″ of FIG. 14B may be substituted foroperations 1145 a, 1145 b, and 1145 c of FIG. 11C. With fixed mapping,one of operations 1145 a, 1145 b, and 1145 c, operations 1145 a′, 1145b′, and 1145 c′, or operations 1145 a″, 1145 b″, and 1145 c″ may alwaysbe used. With dynamic mapping different ones of operations 1145 a, 1145b, and 1145 c, operations 1145 a′, 1145 b′, and 1145 c′, or operations1145 a″, 1145 b″, and 1145 c″ may be selected for a particular TFRE/TTI,for example, based on a mapping selection received from wirelessterminal 200 at block 1140.

At block 1146, spreader scrambler 409 and/or layer precoder 411 mayprecode symbols of the first, second, and third mapped symbol blocks torespective first, second, and third MIMO layers using a MIMO precodingvector to provide precoded symbols of the first, second, and third MIMOlayers. At block 1147, the precoded symbols of the first, second, andthird MIMO precoding layers may be transmitted through the MIMO antennaelements of MIMO antenna array 117 to wireless terminal 200 using a sameTFRE.

When data is available for transmission/retransmission to wirelessterminal 200 for a next TFRE/TTI at block 1148, base station 100 mayselect a rank, a precoding vector, a modulation and coding scheme, atransport block size, etc. for transmission at block 1149, and basestation 100 may transmit identification(s)/indication(s) of the selectedtransmission characteristics (e.g., rank, precoding vector, MCS, TBS,etc.) to the wireless terminal 200. If rank 3 is maintained at block1150, operations of blocks 1140-1150 may be repeated for each rank 3TFRE/TTI. If a different rank (e.g., rank 1, 2, or 4) is selected atblocks 1149 and 1150, base station processor 101 may return to block1015 of FIG. 10 as indicated by block 1151.

If rank 4 transmission is selected for the TFRE/TTI at blocks 1013,1015, and/or 1019 of FIG. 10, base station 100 may proceed withoperations of FIG. 11D. For example, transport block generator 401 mayprovide input data for transmission to the wireless terminal 200 atblock 1161, and separate the input data into first, second, third, andfourth data blocks at block 1162. At block 1163, encoder 403 may encodethe first, second, third, and fourth data blocks at block 1163 togenerate respective first, second, third, and fourth data codewords; andat block 1144, modulator 405 may modulate data of the first, second,third, and fourth data codewords to provide symbols of respective first,second, third, and fourth unmapped symbol blocks. As discussed ingreater detail below regarding some embodiments, a mapping selection maybe received from wireless terminal 200 at block 1160 with the mappingselection defining a mapping of symbols from unmapped symbol blocks tomapped symbol blocks. According to some other embodiments, a mapping ofsymbols from unmapped symbol blocks may be fixed, or one of a pluralityof mapping selections may be selected by base station without receivinginput from wireless terminal 200.

In accordance with Rank 4, Option 2 (discussed above with respect toFIGS. 4 and 5 and shown in FIG. 11D), layer mapper 407 may map symbolsfrom the first unmapped symbol block to first and fourth mapped symbolblocks at block 1165 a; layer mapper 407 may map symbols from the secondunmapped symbol block to second and third mapped symbol blocks at block1165 b; layer mapper 407 may map symbols from the third unmapped symbolblock to the second and third mapped symbol blocks at block 1165 c; andlayer mapper 407 may map symbols from the fourth unmapped symbol blockto the first and fourth mapped symbol blocks at block 1165 d.Accordingly, the first mapped symbol block may include symbols of thefirst and fourth unmapped symbol blocks; the second mapped symbol blockmay include symbols of the second and third unmapped symbol blocks; thethird mapped symbol block may include symbols of the second and thirdunmapped symbol blocks; and the fourth mapped symbol block may includesymbols of the first and fourth unmapped symbol blocks. For example,even symbols of the first and fourth unmapped symbol blocks may map tothe first mapped symbol block, even symbols of the second and thirdunmapped symbol blocks may map to the second mapped symbol block, oddsymbols of the second and third unmapped symbol blocks may map to thethird mapped symbol block, and odd symbols of the first and fourthunmapped symbol blocks may map to the fourth mapped symbol block. Withfixed mapping, for example, rank 3, option 1 (discussed above withrespect to FIG. 11C) and rank 4, option 2 may be used to maintain amapping of second and third unmapped symbol blocks to second and thirdmapped symbol blocks for rank 3 and rank 4 transmissions.

In accordance with Rank 4, Option 1 (discussed above with respect toFIGS. 4 and 5 and shown in FIG. 14C), layer mapper 407 may map symbolsfrom the first unmapped symbol block to first and third mapped symbolblocks at block 1165 a′; layer mapper may map symbols from the secondunmapped symbol block to second and fourth mapped symbol blocks at block1165 b′; layer mapper 407 may map symbols from the third unmapped symbolblock to the first and third mapped symbol blocks at block 1165 c′; andlayer mapper 407 may map symbols from the fourth unmapped symbol blockto the second and fourth mapped symbol blocks at block 1165 d′.Accordingly, the first mapped symbol block may include symbols of thefirst and third unmapped symbol blocks; the second mapped symbol blockmay include symbols of the second and fourth unmapped symbol blocks; thethird mapped symbol block may include symbols of the first and thirdunmapped symbol blocks; and the fourth mapped symbol block may includesymbols of the second and fourth unmapped symbol blocks. For example,even symbols of the first and third unmapped symbol blocks may map tothe first mapped symbol block, even symbols of the second and fourthunmapped symbol blocks may map to the second mapped symbol block, oddsymbols of the first and third unmapped symbol blocks may map to thethird mapped symbol block, and odd symbols of the second and fourthunmapped symbol blocks may map to the fourth mapped symbol block.

In accordance with Rank 4, Option 3 (discussed above with respect toFIGS. 4 and 5 and shown in FIG. 14D), layer mapper 407 may map symbolsfrom the first unmapped symbol block to first and second mapped symbolblocks at block 1165 a″; layer mapper 407 may map symbols from thesecond unmapped symbol block to the first and second mapped symbolblocks at block 1165 b″; layer mapper 407 may map symbols from the thirdunmapped symbol block to third and fourth mapped symbol blocks at block1165 c′; and layer mapper 407 may map symbols from the fourth unmappedsymbol block to the third and fourth mapped symbol blocks at block 1165d″. Accordingly, the first mapped symbol block may include symbols ofthe first and second unmapped symbol blocks; the second mapped symbolblock may include symbols of the first and second unmapped symbolblocks; the third mapped symbol block may include symbols of the thirdand fourth unmapped symbol blocks; and the fourth mapped symbol blockmay include symbols of the third and fourth unmapped symbol blocks. Forexample, even symbols of the first and second unmapped symbol blocks maymap to the first mapped symbol block, odd symbols of the first andsecond unmapped symbol block may map to the second mapped symbol block,even symbols of the third and fourth unmapped symbol blocks may map tothe third mapped symbol block, and odd symbols of the third and fourthunmapped symbol blocks may map to the fourth mapped symbol block.

Operations 1165 a′, 1165 b′ 1165 c′, and 1165 d′ of FIG. 14C may besubstituted for operations 1165 a, 1165 b, 1165 c, and 1165 d of FIG.11D, or operations 1165 a″, 1165 b″ 1145 c″, and 1165 d″ of FIG. 14D maybe substituted for operations 1165 a, 1146 b, 1165 c, and 1165 d of FIG.11D. With fixed mapping, one of operations 1165 a, 1165 b, 1165 c, and1165 d, operations 1165 a′, 1165 b′, 1165 c′, and 1165 d′, or operations1165 a″, 1165 b″, 1165 c″, and 1165 d, may always be used. With dynamicmapping, different ones of operations 1165 a, 1165 b, 1165 c, and 1165d, operations 1165 a′, 1165 b′, 1165 c′, and 1165 d′, or operations 1165a″, 1165 b″, 1165 c″, and 1165 d″ may be selected for a particularTFRE/TTI, for example, based on a mapping selection received fromwireless terminal 200 at block 1160.

At block 1166, spreader scrambler 409 and/or layer precoder 411 mayprecode symbols of the first, second, third, and fourth mapped symbolblocks to respective first, second, third, and fourth MIMO layers usinga MIMO precoding vector to provide precoded symbols of the first,second, third, and fourth MIMO layers. At block 1167, the precodedsymbols of the first, second, third, and fourth MIMO precoding layersmay be transmitted through the MIMO antenna elements of MIMO antennaarray 117 to wireless terminal 200 using a same TFRE.

When data is available for transmission/retransmission to wirelessterminal 200 for a next TFRE/TTI at block 1168, base station 100 mayselect a rank, a precoding vector, a modulation and coding scheme, atransport block size, etc. for transmission at block 1169, and basestation 100 may transmit identification(s)/indication(s) of the selectedtransmission characteristics (e.g., rank, precoding vector, MCS, TBS,etc.) to the wireless terminal 200. If rank 4 is maintained at block1170, operations of blocks 1160-1170 may be repeated for each rank 4TFRE/TTI. If a different rank (e.g., rank 1, 2, or 3) is selected atblocks 1169 and 1170, base station processor 101 may return to block1015 of FIG. 10 as indicated by block 1171.

FIG. 12 illustrates base station operations according to still otherembodiments. Transport block generator 401 may provide input data fortransmission to wireless terminal 200 at block 1201, and separate theinput data into a plurality of different data blocks at block 1203.Encoder 403 may encode a first data block of the plurality of differentdata blocks using a first channel code characteristic to provide a firstdata codeword at block 1205, and modulator 405 may modulate data of thefirst data codeword to provide a first unmapped symbol block at block1207. At block 1209, layer mapper may map symbols of a first unmappedsymbol block to first and second mapped symbol blocks, so that the firstmapped symbol block includes symbols of the first unmapped symbol block,and so that the second mapped symbol block includes symbols of the firstunmapped symbol block. At block 1211, spreader/scrambler 409 and/orlayer precoder 411 may precode the symbols of the first and secondmapped symbol blocks to provide precoded symbols of first and secondMIMO precoding layer using a MIMO precoding vector, and at block 1213,the first and second MIMO precoding layers may be transmitted throughthe MIMO antenna array 117 to wireless terminal 200 using a same TFRE.When additional data is available for transmission at block 1215,operations of FIG. 12 may be repeated.

According to some embodiments of FIG. 12, for example, even symbols ofthe unmapped symbol block may be mapped to the first mapped symbolblock, odd symbols of the unmapped symbol block may be mapped to thesecond mapped symbol block, and the first and second mapped symbolblocks may exclude symbols of any unmapped symbol blocks other than thefirst unmapped symbol block.

According to some other embodiments of FIG. 12, a second data block ofthe plurality of data blocks may be encoded using the first channel codecharacteristic to provide a second data codeword at block 1205.Moreover, modulating data of the first data codeword at block 1207 mayinclude interleaving and modulating data of the first and second datacodewords to provide the first unmapped symbol block. Two separatelyencoded data codewords may thus be interleaved (combined) and modulatedto provide one unmapped symbol block, symbols of which are then mappedto two different MIMO layers for transmission during a same TFRE/TTI.

FIG. 13 illustrates base station operations according to yet otherembodiments. Transport block generator 401 may provide input data fortransmission to the wireless terminal 200 at block 1301, and separatethe input data into a plurality of different data blocks at block 1303.Encoder 403 may encode first and second ones of the plurality ofdifferent data blocks using respective first and second channel codecharacteristics to provide respective first and second data codewords atblock 1305. Moreover, the first and second channel code characteristicsmay be different. Modulator 405 may modulate data of the first andsecond data codewords to provide symbols of respective first and secondunmapped symbol blocks at block 1307. At block 1309 a, layer mapper 407may map symbols of the first unmapped symbol block to first and secondmapped symbol blocks, and at block 1309 b, layer mapper 407 may mapsymbols of the second unmapped symbol block to the first and secondmapped symbol blocks. Accordingly, the first mapped symbol block mayinclude symbols of the first and second unmapped symbol blocks and thesecond mapped symbol block may include symbols of the first and secondunmapped symbol block.

At block 1311, spreader/scrambler 409 and/or layer precoder 411 mayprecode the symbols of the first and second mapped symbol blocks toprovide precoded symbols of respective first and second MIMO precodinglayers using a MIMO precoding vector, and at block 1313, each of theprecoded symbols of the first and second MIMO precoding layers may betransmitted through the MIMO antenna array 117 to wireless terminal 200using a same TFRE/TTI. When additional data is available fortransmission at block 1315, operations of FIG. 13 may be repeated.

FIGS. 15 and 16A-D are flow charts illustrating operations of wirelessterminal 200 corresponding to operations of base station 100 discussedabove with respect to FIGS. 10 and 11A-D. When data is to be received atwireless terminal 200 at block 1501, wireless terminal 200 may receiveidentification(s)/indication(s) of one or more of a rank, a precodingvector (also referred to as a decoding vector), a modulation and codingscheme, a transport block size, etc. from base station 100. Based on therank identified/indicated at blocks 1501 and 1503 for a given TFRE/TTI,operations of FIG. 16A may be performed for rank 1 reception for thegiven TFRE/TTI as indicated at block 1505, operations of FIG. 16B may beperformed for rank 2 reception for the given TFRE/TTI as indicated atblock 1507, operations of FIG. 16C may be performed for rank 3 receptionfor the given TFRE/TTI as indicated at block 1509, and operations ofFIG. 16D may be performed for rank 4 reception for the given TFRE/TTI asindicated at block 1511. In general, wireless terminal 200 receptionoperations of FIGS. 15, 16A, 16B, 16C, and 16D may respectivelycorrespond to base station 100 transmission operations of FIGS. 10, 11A,11B, 11C, and 11D, discussed above.

If rank 1 reception is indicated for the TFRE/TTI at blocks 1501, 1503,and 1505 of FIG. 15, wireless terminal 200 may proceed with operationsof FIG. 16A. For example, layer decoder 601 may decode radio frequencysignals received through the MIMO antenna array 217 using a rank 1 MIMOdecoding vector to generate a decoded symbol block for a first receptionlayer at block 1521. At block 1523, layer demapper 603 may demap symbolsof the decoded symbol block an unmapped symbol block so that theunmapped symbol block includes all symbols of the decoded symbol block.At block 1525, demodulator/deinterleaver DM1 may demodulate the unmappedsymbol block to generate data of a codeword, and at block 1527, channeldecoder CD1 may channel decode the codeword to provide a data block. Atblock 1529, the data block of the rank 1 TFRE/TTI may be combined bytransport block combiner 607 into an output data stream.

When a next reception TFRE/TTI is indicated by base station 100 at block1531, wireless terminal 200 may receive identification(s)/indication(s)of one or more of a rank, a precoding vector, a modulation and codingscheme, a transport block size, etc. from base station 100 for the nextTFRE/TTI. If rank 1 is maintained at block 1535, operations of blocks1521-1531 may be repeated for each rank 1 TFRE/TTI. If a different rank(e.g., rank 2, 3, or 4) is selected at blocks 1531 and 1535, wirelessterminal processor 101 may return to block 1503 of FIG. 15 as indicatedby block 1537.

If rank 2 reception is indicated for the TFRE/TTI at blocks 1501, 1503,and 1507 of FIG. 15, wireless terminal 200 may proceed with operationsof FIG. 16B. For example, layer decoder 601 may decode radio frequencysignals received through the MIMO antenna array 217 using a rank 2 MIMOdecoding vector to generate first and second decoded symbol blocks forfirst and second reception layers at block 1541 for the rank 2 TFRE/TTI.At block 1542, layer demapper 603 may demap symbols of the first andsecond decoded symbol blocks to respective first and second unmappedsymbol blocks so that the first unmapped symbol block includes allsymbols of the first decoded symbol block, and so that the secondunmapped symbol block includes all symbols of the second decoded symbolblock. At block 1543, demodulators/deinterleavers DM1 and DM2 maydemodulate the first and second unmapped symbol blocks to generate dataof first and second data codewords of the rank 2 TFRE/TTI, and at block1544, channel decoders CD1 and CD2 may channel decode the first andsecond data codewords to provide a respective first and second datablocks. At block 1545, the first and second data blocks of the rank 2TFRE/TTI may be combined by transport block combiner 607 into the outputdata stream.

When a next reception TFRE/TTI is indicated by base station 100 at block1546, wireless terminal 200 may receive identification(s)/indication(s)of one or more of a rank, a precoding vector, a modulation and codingscheme, a transport block size, etc. from base station 100 for the nextTFRE/TTI. If rank 2 is maintained at block 1547, operations of blocks1541-1546 may be repeated for each rank 2 TFRE/TTI. If a different rank(e.g., rank 1, 3, or 4) is selected at blocks 1546 and 1547, wirelessterminal processor 101 may return to block 1503 of FIG. 15 as indicatedby block 1548.

If rank 3 reception is indicated for the TFRE/TTI at blocks 1501, 1503,and 1509 of FIG. 15, wireless terminal 200 may proceed with operationsof FIG. 16C. For example, layer decoder 601 may decode radio frequencysignals received through the MIMO antenna array 217 using a rank 3 MIMOdecoding vector to generate first, second, and third decoded symbolblocks for first, second, and third reception layers at block 1551 forthe rank 3 TFRE/TTI. At block 1553 a, layer demapper 603 may demapsymbols of the first decoded symbol block to a first unmapped symbolblock so that the first unmapped symbol block includes all symbols ofthe first decoded symbol block. At block 1553 b, layer demapper 603 maydemap symbols (e.g., even symbols) of the second and third decodedsymbol blocks to a second unmapped symbol block so that the secondunmapped symbol block includes a first half of the symbols of the secondand third decoded symbol blocks. At block 1553 c, layer demapper 603 maydemap symbols (e.g., odd symbols) of the second and third decoded symbolblocks to a third unmapped symbol block so that the third unmappedsymbol block includes a second half of the symbols of the second andthird decoded symbol blocks. At block 1555, demodulators/deinterleaversDM1, DM2, and DM3 may respectively demodulate the first, second, andthird unmapped symbol blocks to generate data of first, second, andthird data codewords of the rank 3 TFRE/TTI, and at block 1557, channeldecoders CD1, CD2, and CD3 may channel decode the first, second, andthird data codewords to provide a respective first, second, and thirddata blocks. At block 1559, the first, second, and third data blocks ofthe rank 3 TFRE/TTI may be combined by transport block combiner 607 intothe output data stream.

When a next reception TFRE/TTI is indicated by base station 100 at block1561, wireless terminal 200 may receive identification(s)/indication(s)of one or more of a rank, a precoding vector, a modulation and codingscheme, a transport block size, etc. from base station 100 for the nextTFRE/TTI. If rank 3 is maintained at block 1555, operations of blocks1551-1561 may be repeated for each rank 3 TFRE/TTI. If a different rank(e.g., rank 1, 2, or 4) is selected at blocks 1561 and 1565, wirelessterminal processor 101 may return to block 1503 of FIG. 15 as indicatedby block 1567.

If rank 4 reception is indicated for the TFRE/TTI at blocks 1501, 1503,and 1511 of FIG. 15, wireless terminal 200 may proceed with operationsof FIG. 16D. For example, layer decoder 601 may decode radio frequencysignals received through the MIMO antenna array 217 using a rank 4 MIMOdecoding vector to generate first, second, third, and fourth decodedsymbol blocks for first, second, third, and fourth reception layers atblock 1581 for the rank 4 TFRE/TTI. At block 1583 a, layer demapper 603may demap symbols (e.g., even symbols) of the first and fourth decodedsymbol blocks to a first unmapped symbol block so that the firstunmapped symbol block includes a first half of the symbols of the firstand fourth decoded symbol blocks. At block 1583 b, layer demapper 603may demap symbols (e.g., even symbols) of the second and third decodedsymbol blocks to a second unmapped symbol block so that the secondunmapped symbol block includes a first half of the symbols of the secondand third decoded symbol blocks. At block 1553 c, layer demapper 603 maydemap symbols (e.g., odd symbols) of the second and third decoded symbolblocks to a third unmapped symbol block so that the third unmappedsymbol block includes a second half of the symbols of the second andthird decoded symbol blocks. At block 1583 d, layer demapper 603 maydemap symbols (e.g., odd symbols) of the first and fourth decoded symbolblocks to a fourth unmapped symbol block so that the fourth unmappedsymbol block includes a second half of the symbols of the first andfourth decoded symbol blocks. At block 1585, demodulators/deinterleaversDM1, DM2, DM3, and DM4 may respectively demodulate the first, second,third, and fourth unmapped symbol blocks to generate data of first,second, third, and fourth data codewords of the rank 4 TFRE/TTI. Atblock 1587, channel decoders CD1, CD2, CD3, and CD4 may channel decodethe first, second, third, and fourth data codewords to providerespective first, second, third, and fourth data blocks. At block 1589,the first, second, third, and fourth data blocks of the rank 4 TFRE/TTImay be combined by transport block combiner 607 into the output datastream.

When a next reception TFRE/TTI is indicated by base station 100 at block1591, wireless terminal 200 may receive identification(s)/indication(s)of one or more of a rank, a precoding vector, a modulation and codingscheme, a transport block size, etc. from base station 100 for the nextTFRE/TTI. If rank 4 is maintained at block 1595, operations of blocks1581-1591 may be repeated for each rank 4 TFRE/TTI. If a different rank(e.g., rank 1, 2, or 3) is selected at blocks 1591 and 1595, wirelessterminal processor 101 may return to block 1503 of FIG. 15 as indicatedby block 1597.

In the above-description of various embodiments of present inventiveconcepts, it is to be understood that the terminology used herein is forthe purpose of describing particular embodiments only and is notintended to be limiting of present inventive concepts. Unless otherwisedefined, all terms (including technical and scientific terms) usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which present inventive concepts belong. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of this specification andthe relevant art and will not be interpreted in an idealized or overlyformal sense expressly so defined herein.

When an element is referred to as being “connected”, “coupled”,“responsive”, or variants thereof to another element, it can be directlyconnected, coupled, or responsive to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected”, “directly coupled”, “directly responsive”,or variants thereof to another element, there are no interveningelements present. Like numbers refer to like elements throughout.Furthermore, “coupled”, “connected”, “responsive”, or variants thereofas used herein may include wirelessly coupled, connected, or responsive.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. Well-known functions or constructions may not be described indetail for brevity and/or clarity. The term “and/or” includes any andall combinations of one or more of the associated listed items.

As used herein, the terms “comprise”, “comprising”, “comprises”,“include”, “including”, “includes”, “have”, “has”, “having”, or variantsthereof are open-ended, and include one or more stated features,integers, elements, steps, components or functions but does not precludethe presence or addition of one or more other features, integers,elements, steps, components, functions or groups thereof. Furthermore,as used herein, the common abbreviation “e.g.”, which derives from theLatin phrase “exempli gratia,” may be used to introduce or specify ageneral example or examples of a previously mentioned item, and is notintended to be limiting of such item. The common abbreviation “i.e.”,which derives from the Latin phrase “id est,” may be used to specify aparticular item from a more general recitation.

It will be understood that although the terms first, second, third, etc.may be used herein to describe various elements/operations, theseelements/operations should not be limited by these terms. These termsare only used to distinguish one element/operation from anotherelement/operation. Thus a first element/operation in some embodimentscould be termed a second element/operation in other embodiments withoutdeparting from the teachings of present inventive concepts. The samereference numerals or the same reference designators denote the same orsimilar elements throughout the specification.

Example embodiments are described herein with reference to blockdiagrams and/or flowchart illustrations of computer-implemented methods,apparatus (systems and/or devices) and/or computer program products. Itis understood that a block of the block diagrams and/or flowchartillustrations, and combinations of blocks in the block diagrams and/orflowchart illustrations, can be implemented by computer programinstructions that are performed by one or more computer circuits. Thesecomputer program instructions may be provided to a processor circuit ofa general purpose computer circuit, special purpose computer circuit,and/or other programmable data processing circuit to produce a machine,such that the instructions, which execute via the processor of thecomputer and/or other programmable data processing apparatus, transformand control transistors, values stored in memory locations, and otherhardware components within such circuitry to implement thefunctions/acts specified in the block diagrams and/or flowchart block orblocks, and thereby create means (functionality) and/or structure forimplementing the functions/acts specified in the block diagrams and/orflowchart block(s).

These computer program instructions may also be stored in a tangiblecomputer-readable medium that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablemedium produce an article of manufacture including instructions whichimplement the functions/acts specified in the block diagrams and/orflowchart block or blocks.

A tangible, non-transitory computer-readable medium may include anelectronic, magnetic, optical, electromagnetic, or semiconductor datastorage system, apparatus, or device. More specific examples of thecomputer-readable medium would include the following: a portablecomputer diskette, a random access memory (RAM) circuit, a read-onlymemory (ROM) circuit, an erasable programmable read-only memory (EPROMor Flash memory) circuit, a portable compact disc read-only memory(CD-ROM), and a portable digital video disc read-only memory(DVD/BlueRay).

The computer program instructions may also be loaded onto a computerand/or other programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer and/or otherprogrammable apparatus to produce a computer-implemented process suchthat the instructions which execute on the computer or otherprogrammable apparatus provide steps for implementing the functions/actsspecified in the block diagrams and/or flowchart block or blocks.Accordingly, embodiments of present inventive concepts may be embodiedin hardware and/or in software (including firmware, resident software,micro-code, etc.) that runs on a processor such as a digital signalprocessor, which may collectively be referred to as “circuitry,” “amodule” or variants thereof.

It should also be noted that in some alternate implementations, thefunctions/acts noted in the blocks may occur out of the order noted inthe flowcharts. For example, two blocks shown in succession may in factbe executed substantially concurrently or the blocks may sometimes beexecuted in the reverse order, depending upon the functionality/actsinvolved. Moreover, the functionality of a given block of the flowchartsand/or block diagrams may be separated into multiple blocks and/or thefunctionality of two or more blocks of the flowcharts and/or blockdiagrams may be at least partially integrated. Finally, other blocks maybe added/inserted between the blocks that are illustrated, and/orblocks/operations may be omitted without departing from the scope ofpresent inventive concepts. Moreover, although some of the diagramsinclude arrows on communication paths to show a primary direction ofcommunication, it is to be understood that communication may occur inthe opposite direction to the depicted arrows.

Many different embodiments have been disclosed herein, in connectionwith the above description and the drawings. It will be understood thatit would be unduly repetitious and obfuscating to literally describe andillustrate every combination and subcombination of these embodiments.Accordingly, the present specification, including the drawings, shall beconstrued to constitute a complete written description of variousexample combinations and subcombinations of embodiments and of themanner and process of making and using them, and shall support claims toany such combination or subcombination.

Many variations and modifications can be made to the embodiments withoutsubstantially departing from the principles of present inventiveconcepts. All such variations and modifications are intended to beincluded herein within the scope of present inventive concepts.Accordingly, the above disclosed subject matter is to be consideredillustrative, and not restrictive, and the appended claims are intendedto cover all such modifications, enhancements, and other embodiments,which fall within the spirit and scope of present inventive concepts.Thus, to the maximum extent allowed by law, the scope of presentinventive concepts is to be determined by the broadest permissibleinterpretation of the embodiments discussed herein, and shall not berestricted or limited by the foregoing detailed description.

That which is claimed:
 1. A method of receiving data at a wirelessterminal from a radio access network node using amultiple-input-multiple-output, MIMO, antenna array including aplurality of MIMO antenna elements, the method comprising: decodingradio frequency signals received through the MIMO antenna elements ofthe MIMO antenna array using a MIMO decoding vector to generate aplurality of MIMO decoded symbol layers including a first decoded symbolblock of a first of the MIMO decoded symbol layers and a second decodedsymbol block of a second of the MIMO decoded symbol layers, wherein thefirst and second decoded symbol blocks represent data received during asame time-frequency-resource-element; demapping symbols of the first andsecond decoded symbol blocks to a first unmapped symbol block, so thatthe first unmapped symbol block includes symbols of the first and seconddecoded symbol blocks of the respective first and second MIMO decodedsymbol layers; and demapping symbols of the first and second decodedsymbol blocks to a second unmapped symbol block, so that the secondunmapped symbol block includes symbols of the first and second MIMOdecoded symbol blocks.
 2. The method of claim 1 further comprising:demodulating the first unmapped symbol block to generate data of a firstcodeword; demodulating the second unmapped symbol block to generate dataof a second codeword; channel decoding the first codeword using a firstchannel code characteristic to provide a first data block; channeldecoding the second codeword using a second channel code characteristicto provide a second data block wherein the first and second channel codecharacteristics are different; and combining the first and second datablocks to provide an output data stream.
 3. A wireless terminalcomprising: a multiple-input-multiple output, MIMO, antenna arrayincluding a plurality of MIMO antenna elements; a receiver coupled tothe MIMO antenna array wherein the receiver is configured to receiveradio signals from respective antennas of the MIMO antenna array; and aprocessor coupled to the receiver wherein the processor is configured todecode the radio signals received through the receiver using a MIMOdecoding vector to generate a plurality of MIMO decoded symbol layersincluding a first decoded symbol block of a first of the MIMO decodedsymbol layers and a second decoded symbol block of a second of the MIMOdecoded symbol layers, wherein the first and second decoded symbolblocks represent data received during a sametime-frequency-resource-element, to demap symbols of the first andsecond decoded symbol blocks to a first unmapped symbol block so thatthe first unmapped symbol block includes symbols of the first and seconddecoded symbol blocks of the respective first and second MIMO decodedsymbol layers, and to demap symbols of the first and second decodedsymbol blocks to a second unmapped block so that the second unmappedsymbol block includes symbols of the first and second MIMO decodedsymbol blocks.
 4. The wireless terminal of claim 3 wherein the processoris further configured to demodulate the first unmapped symbol block togenerate data of a first codeword, to demodulate the second unmappedsymbol block to generate data of a second codeword, to channel decodethe first codeword using a first channel code characteristic to providea first data block, to channel decode the second codeword using a secondchannel code characteristic to provide a second data block wherein thefirst and second channel code characteristics are different, and tocombine the first and second data blocks to provide an output datastream.
 5. A method of receiving data at a wireless terminal from aradio access network node using a multiple-input-multiple-output, MIMO,antenna array including a plurality of MIMO antenna elements, the methodcomprising: decoding radio frequency signals received through the MIMOantenna elements of the MIMO antenna array using a MIMO decoding vectorto generate a plurality of MIMO decoded symbol layers including a firstdecoded symbol block of a first of the MIMO decoded symbol layers and asecond decoded symbol block of a second of the MIMO decoded symbollayers; demapping symbols of the first and second decoded symbol blocksto a first unmapped symbol block, so that the first unmapped symbolblock includes symbols of the first and second decoded symbol blocks ofthe respective first and second MIMO decoded symbol layers; anddemapping symbols of the first and second decoded symbol blocks to asecond unmapped symbol block, so that the second unmapped symbol blockincludes symbols of the first and second MIMO decoded symbol blocks. 6.The method of claim 5 further comprising: demodulating the firstunmapped symbol block to generate data of a first codeword; demodulatingthe second unmapped symbol block to generate data of a second codeword;channel decoding the first codeword using a first channel codecharacteristic to provide a first data block; channel decoding thesecond codeword using a second channel code characteristic to provide asecond data block wherein the first and second channel codecharacteristics are different; and combining the first and second datablocks to provide an output data stream.
 7. The method of claim 5wherein the first and second decoded symbol blocks represent datareceived using a same time resource.
 8. The method of claim 5 whereinthe first and second decoded symbol blocks represent data received usinga same transmission time interval.
 9. A wireless terminal comprising: amultiple-input-multiple output, MIMO, antenna array including aplurality of MIMO antenna elements; a receiver coupled to the MIMOantenna array wherein the receiver is configured to receive radiosignals from respective antennas of the MIMO antenna array; and aprocessor coupled to the receiver wherein the processor is configured todecode the radio signals received through the receiver using a MIMOdecoding vector to generate a plurality of MIMO decoded symbol layersincluding a first decoded symbol block of a first of the MIMO decodedsymbol layers and a second decoded symbol block of a second of the MIMOdecoded symbol layers, to demap symbols of the first and second decodedsymbol blocks to a first unmapped symbol block so that the firstunmapped symbol block includes symbols of the first and second decodedsymbol blocks of the respective first and second MIMO decoded symbollayers, and to demap symbols of the first and second decoded symbolblocks to a second unmapped symbol block so that the second unmappedsymbol block includes symbols of the first and second MIMO decodedsymbol blocks.
 10. The wireless terminal of claim 9 wherein theprocessor is further configured to demodulate the first unmapped symbolblock to generate data of a first codeword, to demodulate the secondunmapped symbol block to generate data of a second codeword, to channeldecode the first codeword using a first channel code characteristic toprovide a first data block, to channel decode the second codeword usinga second channel code characteristic to provide a second data blockwherein the first and second channel code characteristics are different,and to combine the first and second data blocks to provide an outputdata stream.
 11. The wireless terminal of claim 9 wherein the first andsecond decoded symbol blocks represent data received using a same timeresource.
 12. The wireless terminal of claim 9 wherein the first andsecond decoded symbol blocks represent data received using a sametransmission time interval.
 13. The method of claim 1 wherein thetime-frequency-resource-element comprises a transmission time interval.14. The wireless terminal of claim 3 wherein thetime-frequency-resource-element comprises a transmission time interval.